Layers in the Sand
An original lesson plan/review activity developed by Erin Cziraki.
This activity is intended to be used as a review activity for the topic of velocity. This activity is designed to
take one class period since the major concepts should have already been introduced. However, it can easily
be expanded by allowing the groups to visit all the stations instead of just one.
Level of Inquiry: 3
Scientific Process Skills: observing, measuring, communicating, defining operationally, investigating
A. South Carolina State Standard:
8-5.2: Use the formula for average speed, v=d/t, to solve real world problems.
B. Performance Objectives:
Upon completion of this activity, students will successfully be able to:
a. Recall the formula for average speed
b. Identify the variables involved
c. Recognize and identify appropriate metric units for representing average speed
d. Use the formula to solve real-world problems
C. Body:
Hook: The teacher begins by asking students about the power of waves and what they can do when
they interact with the coast (think tsunamis and the destruction they cause). The students are then
asked what they think happens to the sand/sediment on the beach when huge waves pass though
(sediment gets carried inland). Also, ask what happens to the sediment if an area becomes flooded
and the water stands still for an extended period of time. The teacher can use a settling tube with
three different sediment sizes to demonstrate what might happen. Shake up the tube to represent the
wave impacting the shore and then let the sediment settle. Do this numerous times so the students
can observe what happens. They should notice the distinct layers formed as the sediment settles.
1. Concept Exploration
This activity should be entered in the students lab notebook.
Title: “Velocity Review” or “Layers in the Sand”
Purpose/Question: “Why does the sand end up in layers?”
Hypothesis: Give the students time to write down their initial ideas about why this happens.
Activity: The teacher asks for some students to share their ideas about why the sediment ended up
in layers. The teacher explains that he/she thinks the answer may lie in how fast the different sizes
of sand settle out once the water has stopped moving. The teacher explains that the class is going
to design an experiment to investigate this idea. The teacher asks the class for a list of materials
that they might need to investigate this idea. Be sure to also ask what each tool will be used for.
The class is then divided into groups of four before beginning an activity involving stations and the
groups are asked to figure out their methods for measuring the velocity of a grain of sand as it falls
through the water. Remind the students that they need to do at least three trial runs and that they
should organize their data into a table. Before the groups can move to their stations, they must get
their methods and data table approved by the teacher.
Materials:
Samples of sand that is fine grain, medium grain, and small pebbles
Fine sand can be collected from dunes on the beach
Medium sand can be collected from the swash zone on the beach
Pebbles can either be found or created by breaking up larger rocks
***make sure all sand is DRY for this activity so it doesn’t stick together***
Metric rulers
Stopwatches or other kind of timer
Tall cups, 2-liter bottles, graduated cylinders, etc. for the sand to fall in
Water
The teacher should review the methods with each group to make sure that they have a good idea
of how to find the velocity of sand falling through water. In the interest of time (since this is just
being used for review) have 2 stations for each grain size and have each group work on only one
station, then share their data with the rest of the class. Give the students about 10 minutes to plan
their methods and create their data table, then 15 minutes at their station to conduct their trials.
2. Concept Introduction
Once all of the groups have finished, the teacher asks each group to record the velocity for its grain
size on the class data table written on the board. If the teacher notices any major differences in
the groups’ data, the teacher will ask for possible reasons for why the groups found different
velocities (possible reasons could include operation problems with the stopwatch, the “watcher”
and “timer” not responding quickly enough, distance measurements being taken in inches instead
of centimeters, etc.). The teacher then reviews the concept of velocity, how it is calculated, and
the measurements and units involved.
3. Concept Application
After the teacher completes the Concept Introduction, the students are then asked again why they
think the sand in the sample ended up in layers on the friend’s yard. The students are asked to
relate their answers to the activity they just completed and to reference the data that they
collected. If the students were careful while performing the activity, they will see that the larger
the size of the sand grain, the faster it falls through the water. They should reach the conclusion
that once the water stopped moving, the larger grains dropped to the ground faster than the
medium grains and that the medium grains dropped faster than the smallest grains resulting in the
layers of sand.
D. Review/Evaluation:
The activity packet can be collected and used as an assessment. However, since this is designed for
review purposes, the students’ performance on the test could also be used.
Teacher notes:
Give the students just a small amount of sediment sample to work with so that they don’t just dump the
whole thing into the cup of water. They should add the sediment just a small pinch at a time so they can
accurately measure the velocity of one or a few grains falling at one time.