Formative Assessments
Water Tools
Formative Assessment Teacher Materials
Revised July 2012
Table of Contents
Connecting Student Responses to the Learning Progression (LP) Framework & Suggestions for
Suggestions for Administration of Formative Assessments
Use these formative assessments before you begin lessons related to the relevant topic. They are designed to help you identify where your students are performing on the learning progressions in order to modify instruction to support students in moving to the next level of achievement. You can provide a copy of the assessment for each student to write on and turn in to you, or you can project the formative assessments with an LCD projector, overhead projector, or Smartboard and have students write their responses in their science notebooks.
1
Wash Trash
This is a picture of a dry streambed called a wash. The wash is dry most of the year. When it rains, the wash fills with water. Sometimes people throw trash in the wash. X marks the location on the map below where the picture was taken.
Town C
Lake
9100 ft
Small wash (dry stream bed)
Larger wash (dry stream bed)
Small lake
Town
Key
2500 ft
W
N
S
E
Town B
X
Town A
2600 ft
2600 ft
1.
If someone throws a soda can in the river at the place marked X, where will the trash go when it rains enough to fill the wash with water?
A.
The trash will not go anywhere.
B.
The trash will float to Town B.
C.
The trash will float to Town A.
D.
The trash will float into the Lake.
E.
The trash will float to Town C.
2.
Which choice best describes your reason for where you think the trash will go?
A.
It flows south. G. It flows to the bottom of the picture
B. Lakes flow into streams.
C. Streams flow into lakes.
H. None of the above
I. The rule of Vs
D. It is lower in elevation.
E. There is water.
F. Water flows to connected washes or streams.
J. Tributaries flow into larger rivers.
2
Purpose
This formative assessment requires students to interpret a map representation of a watershed and reason about the direction and drivers of runoff. Students often use rules for interpreting maps that lead to inaccurate answers. For example, they may reason that water flows down the page or south, or that water always flows from a big source of water, such as a lake. The map in this assessment shows that lower elevations are to the northwest, where the lake is. In this assessment, student reasons for the direction of water flow are as important as where they say the water and trash will go.
Target Understanding (Upper Anchor)
To provide a level 4 account of where the trash in the wash would go, students must recognize that water will flow downhill in response to gravity. Furthermore, they must be able to interpret the map to identify where the lowest elevation would be. The target answers would be that the trash floats to Town C because Town C is lower in elevation than any of the other locations on the map.
Suggestions for Instruction
Level 3 Incomplete Science Stories
Use the Drivers and Constraints tool to scaffold students in considering why water flows in the directions that they identify. Students should recognize that gravity pulls water downhill.
Support students in reasoning about how topography constrains the pathway across the surface that the water flows. If students misinterpret lower elevations using the map, help students recognize clues to topography from maps, even if contours are not provided. Activities such as tracing watersheds with maps may help.
Level 2: Force Dynamic Accounts with Mechanisms
Support students in making connections between 3-dimensional models and 2-dimensional maps. Provide opportunities for students to investigate their informal rules but pointing out situations in which water flowing downhill moves from “smaller” to “bigger” water and vice versa. Challenge and support students in developing a model that accounts for both situations.
Similarly, find situations and model situations in which water flows downhill in a northerly direction (e.g., Nile River).
Level 1: Force Dynamic Accounts
Support students in tracing water in three-dimensional space. Begin with more local examples than an entire watershed. For example, walk the school yard to determine where water flows when it rains. Note relative elevations. Next, build the watershed model and relate it to the local topography. Support students in noting that runoff goes somewhere and does not simply float away.
3
Connecting Student Responses to the Learning Progression (LP)
Level Where will the trash go? Why?
E. The trash will float to Town C. D. It is lower in elevation
4 Model-based accounts
3 Incomplete school science stories
2 Forcedynamic with mechanisms
1 Force dynamic
Any of these responses
B. The trash will float to Town B.
C. The trash will float to town A.
D. The trash will float into the Lake.
OR
E. The trash will float to Town C.
Any of these responses
B. The trash will float to Town B.
C. The trash will float to town A.
D. The trash will float into the Lake
Any of these responses:
A. The trash will not go anywhere
F. The trash will float away
Interpretation &
Implications
Recognizes that gravity pulls water down in elevation and correctly interprets map to identify that the lower elevation is to the northwest.
Recognizes that flows downhill, but misinterprets downhill on the map.
D. It is lower in elevation
OR
Any of these responses
I The rule of Vs
H. Tributaries flow into larger rivers
Any of these responses
F. Water flows to connected washes or streams
C. Streams flow into lakes.
A. It flows south.
G. It flows to the bottom of the picture.
Any of these responses:
E. There is water.
J. None of the above.
Correctly identifies the direction, but uses school rules for determining direction of water flow on a map rather than a causal definition that includes drivers of water flow.
Recognizes that water moves from one place to another and provides a mechanism. Uses informal and often incorrect rules to reason about water flow.
Does not trace water moves from one place to another. Recognizes only what is immediately visible.
Does not include a mechanism.
4
Below is a map of a school campus.
School Map
1. If you were looking from the side instead of from above, what would the shape (height) of the land be like across the distance from Point X to Point Y? (Circle the answer you think is the best.)
A D
B E
C F There’s no way to know.
Explain your reasons for your answer.
__________________________________________________________________________________________
__________________________________________________________________________________________
2. Circle which direction you think School Creek is flowing: North South You can’t tell from the map
Explain how you know.
__________________________________________________________________________________________
__________________________________________________________________________________________
5
Purpose
To understand watersheds on maps, students need to be able to translate between 3-dimensional landscapes and 2-dimensional maps. To do so, students should understand how maps (even ones without topo lines) include info about topography. Because surface water flows down due to gravity, locations marked as water on a map will be at a lower elevation compared with land next to the water. Some maps also provide clues about direction of water flow, but that is not the case for this map. With this formative assessment, you can probe your students’ levels of spatial reasoning in translating between 2-dimensional maps and 3-dimensional landscapes. Once you identify challenges students have with map reading and spatial reasoning skills, you will be able to provide focused guidance aimed at helping students 1) create maps that provide accurate information about 3-dimensional landscapes in 2-dimensions, 2) make inferences about landscape topography from 2-dimensional maps, and 3) use their understanding of the driving force of gravity and the constraining factor of topography to make inferences about direction of water flow using maps.
Target Understanding (Upper Anchor)
Students providing level 4 answers are making inferences connecting 2-dimensional maps to 3-dimensional landscapes. Maps that do not include topo lines can still provide info about topography. To understand maps in this sophisticated way, students need to use understanding of runoff processes. Because the driving force of gravity moves surface water to places of lower elevation, a river will be lower in elevation than the land to either side of the river.
Also on many maps, it is possible to make inferences about which direction water is flowing in a river based on clues such as the angle at which a tributary meets a river, and the relative location of an ocean or a lake that a river flows into. (Note that there are circumstances in which a lake can flow into a river – such as a reservoir behind a dam and/or a mountain tarn formed by a glacier). On the school campus map, there are no clues provided to indicate direction of flow of School Creek.
Students providing upper anchor (level 4) responses show some understanding of driving forces (gravity) and constraining factors (e.g., topography). Example responses could look like:
1. D. Playing fields are usually pretty level and in option D, the profile of the land starts out pretty level from point X. I also know that a creek has to be lower than land around the creek because water flows down due to gravity. In option D, the profile of the land dips down then goes back up as you move toward point Y.
2. You can’t tell from the map. There’s no river or other body of water that the creek is flowing into to provide a clue about the direction the water is flowing. I can’t tell if the elevation is higher toward the north part or toward the south part of the school campus, so I can’t tell if the creek is flowing toward the north or toward the south.
6
Connecting Student Responses to the Learning Progression (LP) Framework
This table shows example responses you might expect to see from students responding at different levels on the LP. Note that students’ explanations tend to be more important than the response options they pick for assigning a level of reasoning.
Le vel
If you were looking from side instead of above, what would the shape (height) of the land be like across the distance from Point X to Point Y?
Circle which direction you think School
Creek is flowing
Level Response Descriptions
4
D. ( ) Playing fields are usually pretty level and in D, the land starts out level from X. A creek has to be lower than the land around it because water flows down. In option D, the land dips down where the creek is.
You can’t tell from the map
Sometimes you can tell direction of water from a map, but not here. There are no tributaries, topo lines, or other clues to suggest elevation and direction.
See target understanding description on previous pages.
3
2
B. ( down to the creek. OR
D. ( lower.
A. (
) The land goes
) The creek is
) The line slants up from point X to point Y like line does on map. Land must go up like the line goes up. OR
E. ( bumpy near the creek. OR
) The land is
F. (There’s no way to know) The map doesn’t show the shape of the land.
You can’t tell from the map
The map doesn’t show which way the creek is going.
North. I can tell because the compass is pointing North.
Responses show understanding that the map represents a 3-dimensional landscape and make some inferences about the landscape by looking at the map. However, level 3 students generally do not use drivers and constraining factors to explain what is happening. Thus, they sometimes make mistakes in interpretations and inferences.
Responses begin to connect maps to landscapes.
However, level 2 responses have trouble connecting details of a map representation to a
3-D landscape. While they realize the map is a representation of a place, level 2 students may just describe what they see on map without understanding implicit connection to things like topography in landscape.
1
C. ( flat.
OR
F. Can’t tell.
) The map is
South. Rivers and creeks always go
South.
OR
The water runs down the page.
Responses do not connect 2-D map with 3-D landscape. Responses are very literal, focusing on what’s drawn on flat piece of paper.
Alternatively, responses may say you can’t tell without explaining why.
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Suggestions for Instruction
Level 3: School Science Stories Suggestions
Level 3 students do a pretty good job using spatial reasoning to make sense of maps. You can provide activities that focus on driving forces and constraining factors that determine which way surface water flows, and the clues to direction of surface water flow that are evident on some maps. For example, you might give students maps showing tributaries entering a river and/or a river entering a lake the students are familiar with. Ask students to describe which way water is flowing in the tributary and the river, and to explain how they know.
Encourage students to describe what force moves surface water (i.e., gravity), what factors constrain the direction of surface water flow (i.e., topography), and what you can tell about these things by looking at a map. Level 3 students could also benefit from learning about topo maps, which provide specific info about topography that can be used to understand and predict where water will flow across the surface of a landscape. One USGS lesson for helping students learn to read and understand topo maps is available at http://egsc.usgs.gov/isb/pubs/teach-pack/mapshow/ . National Geographic also has an online lesson in which students make a clay model of a mountain, then translate their model into a topographic map. This lesson is available at http://www.nationalgeographic.com/xpeditions/lessons/01/g68/dogstails.html
. If you use topo map lessons, you can ask students to compare and contrast what information about surface water can be determined by looking at a topo map versus a map without topo lines. If you do not want to work with topo maps, another option is too obtain plastic relief maps of your area. These 3-D maps can be compared with 2-D maps of the same area. By providing the two types of maps together, you can prompt your students to compare the representations of rivers on both maps and look for patterns in things like how tributaries tend to connect to main stems of rivers, and whether rivers tend to flow into lakes and oceans or vice versa. Having relief maps handy while also looking at 2-D maps can help students to consider the driving force of gravity and the constraining factor of topography because the 3-D nature of relief maps makes the effects of gravity and topography more explicit. You can even have students pour water onto a relief map and see what happens!
Level 2: Force-Dynamic Reasoning with Mechanisms Suggestions
Level 2 responses demonstrate understanding that a map is a representation of a landscape. However, students who provide level 2 responses have limited understanding of how the map implicitly represents the landscape. Similar activities as those described for level 1 can also be useful for students who respond at level
2. These activities will help students develop spatial reasoning connecting maps with 3-D landscapes.
Level 1: Force Dynamic Accounts Suggestions
You can help students who give level 1 responses begin to see the connection between 2-D map representations and 3-D landscapes. If you have a creek, river or pond close to your school, print out a map of the area (e.g., using map view on Google Maps) and bring students to the area. Show students the map and ask them to compare the height of the land around the water to the height of the land in and under the water.
What do they notice? Ask students why the land will always be lower where there’s water? Ask students to describe what a map can tell you about the shape of the land. If you don’t have any water near your school, try building a watershed model with your students. After you build and model water movement in the watershed model, ask students to draw a map of the watershed showing where rivers and ponds or lakes are found. Students can label elevation of different places on their maps and the same questions from the first suggested activity can be asked during the watershed modeling activity.
8
Fold Here
Underground Water Version One
In the drawing below, show where the water in the puddle goes when it soaks into the ground. Be sure to show what it looks like underground (label the things you draw underground) and where the water goes (draw arrows to show where the water goes).
9
Underground Water Version Two
Sometimes we get water out of the ground using wells. Draw a picture of what you think it looks like underground where there’s water.
1.
Label the things you draw to help explain your drawing.
2.
Draw arrows showing pathways water could follow in your drawing.
10
Purpose
These formative assessments probe students’ ideas about what groundwater is, and how water moves in and out of the ground water. Version 1 focuses on the process of infiltration. Version 2 includes a connection to the human-engineered system. Both assessments probe student thinking what it looks like underground and where the water exists underground.
Note for Administration
For Underground Water Version One, be sure to show students how to fold the paper so that the top part of the table lies flat and represents the puddle, and the bottom part of the table shows the cross-section below the puddle underground.
Target Understanding (Upper Anchor)
Soil water and groundwater are located within the small pores and cracks between soil and sediment particles. Water displaces the air that was filling these spaces and adheres to the soil and rock particles that make up the ground. When all of the pore spaces are filled with water, the ground is saturated. The top of this saturated zone is the water table. Above the saturated zone, both water and air fill the pore spaces. Within the unsaturated zone, capillary forces can cause the water to move upwards a small amount. However, overall, the force of gravity is stronger than the capillary forces and pulls water downwards.
How much water infiltrates into the ground depends on the porosity and permeability of the soil/sediment.
Porosity is a measure of the volume of pore spaces and permeability is a measure of the connectedness of the pore spaces. In general, larger grain sizes of soil/sediment have greater permeability. More water can infiltrate into the spaces between larger sized materials than into the spaces between smaller sized materials.
Once in the ground, water can follow multiple pathways. Through capillary action, some water near the surface may reach the surface and evaporate into the atmosphere. Some water may be absorbed by plant roots and transpired back into the atmosphere. Most water will flow downwards into the soil towards the groundwater table. Impermeable layers also influence direction of flow of groundwater. Groundwater above an impermeable layer will flow “downhill” in the direction of the downward slope of the impermeable layer.
Gravity is a main driver of groundwater flow. Permeability is a major constraining factor that influences how fast and in which direction groundwater flows. Pressure can also drive water flow underground.
11
Connecting Student Responses to the Learning Progression (LP) Framework & Suggestions for Instruction
This table shows example responses you might expect to see from students responding at different levels on the LP.
Level Description Implications Suggestions for Instruction
4
3
Responses show command of details of system structure and water processes in the subsurface and subsurface/surface boundaries.
Responses include processes like infiltration, percolation, transpiration, and evaporation. They recognize the processes needed for water to enter the ground, move through the ground, and potentially return to the surface or atmosphere.
Responses show both permeable and impermeable layers underground and represent that water flow underground is governed by these layers (e.g., show horizontal flow of groundwater along an impermeable layer). Drawings may also demonstrate sophisticated understanding of water table, unsaturated zone, capillary action, wells, and groundwater discharge to surface.
“The water infiltrates into the ground,” or “The
water soaks into the ground.”
Students responding at level 4 will be able to trace water along multiple pathways underground and explain what drives and constrains groundwater movement and groundwater/surface water interactions.
Push these students to describe potential pathways in detail and explain both the driving forces and constraining factors for each pathway for different types of ground materials. Also, push students to consider what is happening at the microscopic scale inside the pore spaces. For example, have students explain how water near the surface could evaporate and where that water would go. Students at this level can also be engaged in experiences and pressed to develop explanations of how not just gravity, but also pressure, governs the movement of groundwater (e.g., develop explanations for wells and artesian wells).
Level 3 drawings may show water in pore spaces
in sediment or in cracks. The drawings may show multiple layers, but the layers are usually labeled with generic-type names (e.g., grass, dirt, sand).
There is no indication of difference between permeable and impermeable materials or saturated and unsaturated zones. Wells may be vertical pipes in the ground. The water table may not be contiguous with surface water (e.g., a lake may be suspended above the groundwater).
Students who provide Level 3 responses have a sense that water fills the small spaces between soil and sediment particles underground. However, they may still think of the ground materials as fairly homogeneous without much defining structure or constraining factors, such as differences in material sizes. They do not yet think about multiple pathways that water can take underground.
Activities such as testing infiltration rates or permeability of different size sediments and using groundwater models are useful for students at level 3 because they give these students opportunities to explore the relationship between permeability and infiltration rates. Support students in making the connection between the size of the pore spaces, how much water infiltrates and how quickly this happens.
Also have students draw pictures of what they think is happening to the water that infiltrates and how that might look different for the different ground surfaces
12
2
1
“The ground soaks up the water” or “plants use
water.”
Drawings show water underground and may show underground open layers of water, such as an
underground lake or river. Drawings may also show iconic representations of wells as open cylinders with a roof and a pail on a rope.
“Water disappears” or “goes down.”
Response suggests water leaves puddle, but provides no specific indication of where water goes. Drawing may have scribble to represent matter, but few details. Response may refer to area underground as simply “dirt” or “ground.”
Drawing may also show water in humanengineered features such as underground pipes or sewers.
Students providing level 2 responses understand water is going into the ground rather than disappearing. They may indicate an inanimate actor makes water go into the ground, such as “the ground absorbs water.” Responses reveal difficulty understanding scale of openings underground and do not consider how different sized materials affect how much water can soak into ground or how fast the water can soak into ground.
Students providing level 1 responses may have difficulty understanding that water is moving into the ground. They do not yet understand that there is space underground where water can go.
However, they may be able to think about water in structures that they know about, such as pipes or sewers. that they test. Prompt student to consider what happens to the water underground, including what happens to the water near the roots of plants. These students will also benefit from taking a close look at a soil column and drawing pictures of the difference between saturated and unsaturated zones.
Students reasoning at level 2 will also benefit from looking at spaces between sediment particles in either a water column activity or a plastic cup filled with sediment. Emphasize the size of the spaces. Students may compare the size of spaces in two different sediments, such as sand and gravel.
Have students fill clear plastic cups with sediment, such as sand or gravel, and then draw pictures of the sediment, focusing on spaces in between sediment particles.
Students can pour water into the cups and observe how water that soaks into sediment does not disappear, but fills spaces between sediment particles.
13
What Happens to Water Inside a Plant?
Six friends are walking through their neighborhood when they notice someone watering their garden. Andre asks: What happens to the water that enters the plants? Here’s what Andre’s friends respond:
Michael: The plant stores the water.
Jason: The water will eventually come back out into the soil.
Tonya: The water leaves the plant as a gas.
Juanita: The water makes the plant live and grow.
Charles: The plant evaporates the water.
Who do you agree with the most and why? If you disagree with all the responses, please provide your own response.
Which student do you agree with the most? ______________________________
Why?
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
______________________________________
If you disagree with all of the provided responses, provide your own answer to the question, “What happens to the water that enters the plants?”
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
______________________________________
14
Purpose
Transpiration is a major process by which water moves between land and the atmosphere. According to the
United States Geological Survey, 10% of the moisture found in the atmosphere is released by plants through transpiration. Exact transpiration rates vary greatly geographically and are directly influenced by the following factors: temperature; relative humidity; wind and air movement; soil-moisture availability; and type of plant.
Since transpiration involves the conversion of water in plants to water vapor, we consider this an invisible process, i.e., a process you cannot stand around and witness. Therefore, your students may have difficulty picturing how this process works. Through using this formative assessment, you will be able to probe your students’ levels of understanding about transpiration’s role in moving water through and between connected systems. Once you identify challenges students are having with understanding transpiration, you will be able to provide focused guidance aimed at helping students to 1) understand how water moves through plants, and 2) understand how water changes states.
Target Understanding (Upper Anchor)
In order to reason with sophistication about water movement through and between connected systems, as students think about water movement, they need to be able to conserve water across all system boundaries including recognizing water in hidden and invisible places. Students also need to be able to describe systems and processes at multiple scales including the atomic-molecular scale.
Students reasoning at the upper anchor (level 4) should respond to the probe in a way that shows some understanding of transpiration as a process that moves water from a liquid state in a plant to a gaseous state in the atmosphere. Tonya’s response corresponds most appropriately with an upper anchor understanding of transpiration.
15
Connecting Student Responses to the Learning Progression Framework & Suggestions for Instruction
Each person in the scenario offers an answer and a reason that aligns with a level of achievement in the learning progression framework. The descriptions below link each response with a level of achievement and explain the characteristics of student thinking at that level.
Level Responses Description & Implications Suggestions for Instruction
4 Modelbased accounts
Tonya’s Response:
The water leaves the plant as a gas.
Recognizes that the water didn’t disappear and doesn’t stop at just stating the process of evaporation. Traces water from the plant into the atmosphere and recognizes that there is a change of state. May also be able to consider factors that affect rates of transpiration, including temperature, relative humidity, and plant type.
Students will be able to trace the water from the soil into and through plants to water vapor in the air. They will also be able to consider relative rates of transpiration for various types of plants/ vegetation cover.
3 Incomplete school science stories
2 Forcedynamic with mechanisms
1 Force dynamic
Charles’ Response:
The plant evaporates the water.
Michael’s response:
The plant stores the water.
Jason’s response: The water will eventually come back out into the soil.
Juanita’s response:
The water makes the plant live and grow.
Trace water through the plant. Names processes such as transpiration or evaporation.
Does not describe these processes at an atomic-molecular scale and do not account for changes of state.
Begins to trace water through visible pathways.
Recognizes that plants take up water through their roots, but does not trace water out of plants through invisible processes. May reason that the roots or the plant in general must store the water to be able to use it.
Suggests water is something that plants need to grow. Accounts do not trace water into the plant and cannot yet imagine that water might be an invisible gas. They also do not identify processes that move water - water can disappear or re-appear with no apparent reason.
Diagrams or descriptions of evapotranspiration at the atomic-molecular scale may help students in understanding the phase change that takes place.
Support students by making connections to kinetic molecular theory to describe what happens to the water molecules that leave the stomata of the leaves.
Have students put celery or a carnation in a water vase.
Put a small amount of food coloring in the water. Put plastic wrap over the top of the vase so that the only water leaving the vase must move through the plant.
Mark the initial water level on the vase. Allow students to observe the plant for several days and mark the water level on the vase each day. Students should notice the water level decreases and the leaves of the celery or petals of the carnation turn the same color as the water. You may also put a transpiration bag over the top of the celery or carnation to collect the water.
Students should begin to see that the water moves through the plant and eventually out the leaves.
16
Where Can Fertilizer Go?
Here is a map of a school campus.
The person who takes care of the school grounds spread fertilizer on the playing field grass one morning.
That afternoon it rained and some of the fertilizer on the grass mixed with water and lay in puddles on the playing field.
Where do you think the fertilizer could end up?
1.
Do you think the fertilizer mixed with water on the playing field could get into the atmosphere and come back down as rain with fertilizer mixed into it? YES NO
If you think yes, explain how. If you think no, explain why not.
2.
Do you think the fertilizer mixed with water on the field could get into School Creek?
YES NO
If you think yes, explain how. If you think no, explain why not.
3.
Do you think the fertilizer mixed with water on the field could get into the groundwater?
YES NO
If you think yes, explain how. If you think no, explain why not.
4.
Do you think the fertilizer mixed with water could get inside of grass on the playing field?
YES NO
If you think yes, explain how. If you think no, explain why not.
17
Purpose
This formative assessment is designed to help you examine students’ understanding of what type of mixture is formed when fertilizer is mixed with water, and of where fertilizer mixed with water can and cannot move though connected environmental systems. When fertilizer is mixed with water, it forms a solution. Substances in solution can move with water across surface water systems, into and through groundwater systems, and into plants through absorption with water through roots. However, substances in solution do not evaporate or transpire with water when water changes phase from a liquid to a gas and moves into the atmosphere. This understanding is fundamental for citizens who need to consider and make decisions about water quality issues in their communities.
Target Understanding (Upper Anchor)
A solution is a homogenous mixture composed of two or more substances. In solutions, a solute is dissolved in another substance, the solvent. In the fertilizer formative assessment, water is the solvent that dissolves fertilizer, the solute. Homogenous means that the components of the mixture are uniform throughout the solution, and that the solute will not settle out of the solvent. When substances dissolve, they break down at an atomic-molecular level. For example, when salts dissolve in water, they form negative and positive ions that are attracted to the positive and negative ends of the water molecule. Dissolved solutes cannot be filtered from the solvent except under special conditions. For example, in reverse osmosis, pressure is applied to a solution when it is on one side of a selective membrane. The solvent (e.g., water molecules) can move through the selective membrane, but the solute (e.g., sodium and chloride ions in the case of table salt) cannot. In reverse osmosis, the substances in solution would not separate from each other without the added application of pressure.
Students who provide level 4 answers understand that fertilizer (which is composed of macronutrients in compounds that include important elements such as Nitrogen, Phosphorus, and Potassium) dissolves and forms a solution with water. It is important that the ingredients in fertilizer can form a solution with water because our purpose in applying fertilizer is that it will be absorbed through the roots of plants. The nutrients in the fertilizer can then be incorporated into plant tissues during biosynthesis processes in plants.
18
Connecting Student Responses to the Learning Progression (LP) Framework
Rain Creek Groundwater
4
3
2
1
No. Fertilizer mixed with water cannot move into the atmosphere because substances mixed with water do not evaporate with water.
The substances in fertilizer are not volatile at every day temperatures and pressures, so they will not vaporize. Even if some of the stuff in the fertilizer could vaporize, it wouldn’t vaporize with the water, it would happen separately.
Note the difference between
3 and 4 response. Level 4 responses explain why other substances do not evaporate
with water.
Yes. The grass can absorb the fertilizer.
Yes. Fertilizer mixed in water evaporates and turns into fertilizer mixed with rain.
No. Rain comes from the sky, not from the ground. There’s no way water and fertilizer on the ground could turn into rain.
Yes. Fertilizer mixed with water can get into School Creek. If it rains again and the ground is wet and saturated, some of the fertilizer mixed with water could run off downhill toward School Creek with the rain water, running over the surface of the grass toward the creek. Also, fertilizer could move with water through the soil and groundwater toward School Creek, so some fertilizer mixed with water could get into the creek by moving through the ground.
Note the level 4 response provides 2
pathways (runoff and groundwater) and implicitly refers to driver of gravity (by mentioning “downhill”) and constraining factor of how water will infiltrate unless
ground is saturated.
Yes. The fertilizer could seep into the ground-water.
Yes. The playing field is close to School
Creek, so the fertilizer could get into the creek.
No. The fertilizer and water are on the field. The creek is not connected.
Yes. When the fertilizer gets wet, it doesn’t stay in grains, it dissolves in the water.
Dissolved substances can infiltrate into the groundwater and move through with the water.
Water infiltrates into the ground because of gravity.
Note the level 4 response describes multiple scales
(i.e., macroscopic grains and dissolved fertilizer), that dissolved substances can
move through groundwater, and the driving force of
gravity.
Yes. The fertilizer could runoff into School Creek.
Yes. The ground absorbs the fertilizer.
Yes. The grass absorbs the fertilizer. [Note: Says grass, but asked about ground.]
No. Fertilizer can’t get down there.
Plants
Yes. Dissolved substances are broken down at an atomic-molecular level, so dissolved substances are small enough to be absorbed with water into plants through the plants’ roots. This is how nutrients get into plants.
Note level 4 response provides explanation at
atomic-molecular scale.
No. Fertilizer doesn’t evaporate with water.
Yes. Plants drink the water with the fertilizer in it.
No.
No. It can’t get in.
Yes. Plants need fertilizer.
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Suggestions for Instruction
Level 3: School Science Stories Suggestions
Description: Level 3 responses are often show relatively good understanding of water systems and processes. Many times, they reflect stories about where water goes that students learn in science classes. A common characteristic of level 3 responses is that they tell stories of where water and other substances go without describing driving forces that move water and other substances (e.g., gravity, pressure, etc.) or constraining factors that govern where water and other substances will go (e.g., solubility, saturation, heat of vaporization, etc.). Level 3 responses also tend to think of dissolving as breaking down into small bits that you cannot see, but not necessarily understanding that the breaking down is taking place at an atomic molecular scale. Students may confuse things that are breaking down at a very small macroscopic or microscopic scale (i.e., forming a suspension) with things that are dissolving at an atomic-molecular scale.
In question 1, the level 3 response identifies that fertilizer in water will not evaporate with water and return as rain mixed with fertilizer. However, no driving forces or constraining factors are identified to explain why. In question 2, the example response describes that fertilizer in water could runoff into School Creek. However, it does not explain that runoff across a permeable surface usually doesn’t happen unless the substrate underneath is saturated, or that water in a puddle is in a local low spot, and will not likely runoff the ground to a different place unless another large rain event occurs. The level 3 responses to question 2 also only provides one pathway, and does not indicate groundwater as another possible path. The example level 3 response to question 3 does not identify a driving force (gravity) or constraining variables (e.g., permeability, saturation, etc.). It also does not explicitly demonstrate understanding that fertilizer is dissolved in water, and that dissolved substances generally do move through the ground with water, while suspended substances generally do not. The level 3 response to
question 4 demonstrates basic understanding that fertilizer can be absorbed into plants, but does not describe the constraining factor (scale of dissolved substances allowing for absorption of substances with water into plant cells).
Suggestions: Level 3 responses demonstrate pretty good understanding of where water and most substances will go in connected systems. However, students reasoning at level 3 may just view things at atomic-molecular scale as being “really small particles.” Thus, it will be helpful to provide experiences that focus on subtle differences --- such as the fact that microscopic scale particles (e.g., bacteria, particles of silt) will form a suspension in water whereas substances that breakdown or dissolve in water at the atomic-molecular scale (e.g., salts) will form a solution. Explore the difference between solutions and suspensions in different ways. For example, let students experiment with a laser beam to see that particles in suspension will block light, whereas particles in solution will not. You can also use the Powers of Ten materials and online simulations and animations such as those below to help students understand that what is happening at the atomic molecular scale is not the same as what happens with really small bits of macroscopic stuff like particles of sand or dirt. Atoms and ions interact with each other in interesting ways because of inter-molecular forces. These forces do not behave in the
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same ways as macroscopically observable forces that we are more familiar with such as gravity acting on macroscopic objects with mass.
PhET Salts and Solubility Simulation http://phet.colorado.edu/en/simulation/soluble-salts
Flash Movie of Salt Dissolving in Water http://www.mhhe.com/physsci/chemistry/essentialchemistry/flash/molvie1.swf
Level 2: Force-Dynamic Reasoning with Mechanisms Suggestions
Description: Level 2 responses showing growing awareness of connections among systems and movement of materials through and between systems. For example, students reasoning at level two understand that visible substances can mix with each other, but they generally do not understand that substances such as fertilizer can dissolve in water, and still be present in water even if they are “invisible.” So, dissolve might mean the same thing as disappear – something that is dissolved is just gone. Level 2 responses often trace other substances into the atmosphere with evaporating water. Level 2 responses tend to rely on proximity as a determinate of where water and other substances will go (e.g., water and other substances will flow to nearby places). Level 2 responses often use force-dynamic language that invokes inanimate actors doing things. For example, a level 2 response to question 2 might say, “Yes.
The wind could blow the fertilizer into the creek.” The example response to question 3 is another example of force-dynamic language --- with the ground identified as an actor that absorbs the fertilizer.
Suggestions: Students reasoning at level 2 need support to help them understand how water and other substances can move from place to place, and what exactly is happening with phenomena that are hidden or invisible. Similar activities as those suggested for level 1 will also be helpful for level 2. Provide students who give level 2 responses lots of first-hand experiences with phenomena that are usually hidden or invisible, and focus on the how’s and why’s of what’s happening. Students can be introduced to the idea that substances can exist that are too small to see with the human eye. Use the Powers of Ten tool and associated videos in association with solar still activities or activities involving a precipitate left after evaporation to help students understand that dissolved substances are still present in water; they’re just too small to see.
Level 1: Force Dynamic Accounts Description and Suggestions
Description: Level 1 responses do not indicate understanding that water and other substances can move from one place to another when the different places aren’t directly touching each other. However, level 1 responses do often indicate that water can move to “connected” places, so you might see a level 1 response for question 2 such as, “Yes. The playing field is connected to School Creek, so the fertilizer could get in.” Level 1 responses might also just indicate “no,” without providing an explanation for why not. Level 1 responses also consider water in different places or with different qualities to be different “types” of water. Thus, a level 1 response could reflect the idea that rain water is just a different kind of water than puddle water, so the puddle with fertilizer could not “turn into” rain.
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Suggestions: Level 1 students tend to focus on the immediate and visible world. You can help them develop more sophisticated understanding by providing first-hand experiences with phenomena that are usually invisible or hidden from view. For example, you can mix fertilizer with water in a beaker. The fertilizer may seem to disappear when mixed with water. Ask students what they think happened to the fertilizer; is it still in the cup even though we can’t see it? Ask students if they can think of a way to test whether or not the fertilizer is still present.
For example, if you allow the water to evaporate from the beaker, the fertilizer will precipitate out and remain in the bottom of the cup.
Help students observe that water can move from place to place, even places that aren’t
“touching each other.” Go out to the school ground with students and look for evidence of materials that have been moved by water such as sticks or sediments near sewer drains. Ask the students how those materials got there. Then, you might go outside with students on another day during a rainstorm and observe water moving across surfaces on the school ground. Students may see evidence that other materials can move with water as well (e.g., sticks or dirt in water runoff water).
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Where Can Construction Site Dirt Go?
A school is doing a construction project and had to dig up some of the ground around the school.
The project left a lot of dirt exposed on the surface of the ground. One problem is that when it rains, the rain could wash away a lot of the dirt exposed by the construction project. In a rain storm, where might the dirt go?
For each choice below, decide if the dirt would go there, circle YES or NO, and then explain your answer.
Could the dirt get here?
YES or NO
(Circle one)
Explain your answer
A.
Groundwater
B.
A nearby creek that runs by downhill from the school
C.
Inside trees and plants in the undisturbed areas around the school
YES or NO
YES or NO
YES or NO
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Purpose
This formative assessment probes students’ understanding of substances in suspension.
Substances in suspension in water move with water to different places, and unmix from water in different ways from substances in solution. Students do not often make distinctions between substances in suspension and solution when thinking about where substances in water might go or how they mix or separate from water. This formative assessment is designed to help you assess student understanding of how substances in suspension move and separate from water.
Target Understanding (upper anchor)
Suspensions are heterogeneous mixtures. Suspensions are distinguished from solutions based on two important characteristics. First, substances in suspension are generally of a larger particle size than substances in solution. Second, substances in suspension do not break apart into smaller components. For example, sediment mixed with water remains sediment. In a solution, however, the substances break apart, such as when salt mixed with water breaks apart into sodium ions and chloride ions. As a result of these features, substances in suspension behave differently than substances in solution. Substances in suspension can be filtered out of water with common filters, whereas substances in solution can only be filtered out at the atomic scale, such as through reverse osmosis 1 . Substances in suspension will generally settle out of suspension due to gravity, whereas substances in solution will not settle out. Similarly, substances in suspension are usually visible in the water, making the water appear cloudy or opaque. Substances in solution will not be visible.
When considering where substances move with water, substances in suspension will not move into the groundwater because they are generally filtered out by the small pores in the soil.
Similarly, substances in suspension will not move into plant roots. Substances in suspension will move with surface water into streams, rivers, and lakes. However, depending on the particle size and the velocity of the water, substances in suspension may settle out of slow moving water or still water. Substances in suspension will not evaporate with water into the atmosphere .
1 In reverse osmosis, pressure is applied to a solution when it is on one side of a selective membrane.
The solvent (e.g., water molecules) can move through the selective membrane, but the solute (e.g., sodium and chloride ions) cannot.
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Connecting Student Responses to the Learning Progression Framework
4
3
A.
Groundwater
No –The pores in the soil/ground are too small for the dirt to move through and the dirt will be filtered out.
No – Dirt will not go with the water into the ground.
B.
A nearby creek C. Inside trees and plants
Yes – The tiny dirt particles are in suspension and will be carried with the water as it runsoff down to the stream because of gravity.
Yes – The dirt goes with the water to the creek.
No – The openings in the plant roots are too small for the dirt particles to move through and the dirt will be filtered out.
No – Dirt does not move with water into trees and plants.
2
1
Yes - The dirt will go into the groundwater because the water goes into the groundwater.
Yes – The dirt could fall into the groundwater.
Yes – The ground absorbs the dirt.
Yes – The dirt dissolves into the ground.
No – The ground cleans the water.
No –
No – The dirt cannot get underground.
Yes – Dirty water is underground.
Yes – If the water from the school is connected to the creek.
Yes - The wind blows the dirt into the creek.
No – The creek is not connected to the dirt at the school.
No - The dirt is not near the creek.
No -
Yes – The creek is dirty
No – The dirt doesn’t move.
Interpretation
Explains what happens to materials in suspension in at a microscopic scale. Accounts for constraining factors such as water velocity and pore size that determine if substances in suspension will separate from water.
No – The dirt cannot go into the plants.
Yes – If the plants drink the dirty water.
No –
No – The dirt doesn’t move.
No – Plants don’t drink dirt.
Provides school science stories about what happens to the dirt in the water, such as that dirt in water is filtered out of the groundwater and does not flow into plants. Generally written at the macroscopic scale. Does not describe factors, such as pore size, that limit dirt moving through the soil. Does not identify substances in suspension or distinguish between substances in suspension or solution.
Recognizes that there can be visible materials that mix with water, such as dirt, leaves, or trash. They also provide answers that include mechanisms for mixing those materials with water or separating those materials from water. Usually, answers include inanimate actors that do something to either the water or the dirt in the water(e.g., example: “the ground absorbs water or dirt,” “the plants
might drink dirty water,” or “the ground cleans the water.”) Responses usually only describe phenomena students can see or observe. May describe water mixing with dirt to make mud, or water soaking into the ground.
Provides descriptions of different types of water (e.g., water + dirt = “dirty water,”) indicating water is not a mixture. Does not trace substances in water from place to place. Places like groundwater or the inside of plants would be invisible or hidden students may not think either water or dirt would go there
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Suggestions for Instruction:
Level 3: Incomplete School Science Stories
Provide students with opportunities to closely examine the top of the soil column before and after pouring water through the column. Can they see the pore spaces? After pouring water mixed with dirt through the column, can they see the dirt clogging up the pore spaces? You could provide students with opportunities to pour water through different size materials in the soil column, such as gravel with larger pore spaces or very fine sand with smaller pore spaces to see the influence of pour size on how much dirt is filtered out. Support students in making the connection to the reason why dirt is not absorbed by plants (the openings in the roots are too small). You could also have students more closely observe the velocity of water in the water chute. Are there places where the velocity is faster or slower? What happens to dirt mixed with water in the slower spaces? Point out that larger grain sizes will settle out first and smaller grain sizes will be carried further.
It would also be appropriate to begin making the distinction between suspensions and solutions at the atomicmolecular scale. Use drawings to help students draw representations of substances in suspension vs. substances in solution. Emphasize the size difference and help students recognize that dirt particles
(suspensions) are much larger than ions of materials in solution. If your students have experience with Powers of Ten charts, they might plot the size of substances in suspension and compare them to the size of ions of substances in solution (e.g., sodium chloride)
Level 2: Force Dynamic Accounts with Mechanisms
Provide students with many experiences watching what happens when water mixed with dirt moves through different media. Have students first pour water thought a coffee filter to see how the filter prevents the dirt from moving through. Then have students observe what happens when water mixed with dirt is poured through the column of soil to help students see how the soil actually serves as a filter in the same way that the coffee filter works. Also, have students make careful observations of the dirt in the water moving across an impermeable surface, such as a paint tray. You may also have students observe dirt settle out of water in a beaker of water left undisturbed for several days. The celery activities and solar still activities will also provide students with additional experiences watching substances move or not move with water.
Level 1: Force-dynamic Accounts
Provide students with opportunities to look for evidence that water moves dirt, leaves, or other materials.
When you are outside, have students look for evidence that water moves dirt, leaves, or other materials. For example, students might find places where dirt was washed onto a sidewalk. Have students figure out the source of the dirt on the sidewalk. You can also pout water onto some unvegetated soil and have students draw picture or write about how the water mixes and moves with the water.
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