Fourth-Fifth Grade
Mixtures and Solutions - LESSON 3
INTENDED CURRICULUM
BIG IDEA: (display in class during the lesson)
Elements and their combinations account for all the varied types of matter around us.
Idaho Standard(s) addressed:
5.S.2.1.1 Describe the differences among elements, compounds, and mixtures.
LESSON CONTENT GOALS
1) Matter is made of atoms.
2) Each pure compound is composed of a
specific set of atoms.
3) Each type of compound has its own
individual properties and behaviors.
ii
GUIDINGQUESTIONS
1) What is the smallest unit that makes up
all matter?
2) What is a pure compound?
3) How are pure compounds different from
one another?
TESLA Mixtures and Solutions Lesson 3 – Separating a Salt Solution DRAFT 07/26/13
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IMPLEMENTED
CURRICULUM
Teacher’s Notes:
Useful science concepts to know:
(1) It is not possible for students to do an experiment that proves the existence of atoms. Scientists
struggled for centuries to do it and it is surprisingly difficult to accomplish. You will have to tell
your students about the existence atoms.
(2) The terms “molecule” and “compound” are used interchangeably here. There are some subtle
differences in the terms, but the differences are not important for this unit.
(3) The solid in LE2 was table salt (NaCl), which formed from the elements sodium (Na) and
chloride (Cl). In this lesson, the solid is Epsom Salt (MgSO4), is composed of the elements
magnesium (Mg), sulfur (S) and oxygen (O). Both NaCl and MgSO4 are referred to as “salts”
because they are composed of charged particles (this is not important to this unit…I am telling you
in case you are wondering). While these salts initially look very similar, they have different
properties. For example, NaCl forms a crystal with an “x” through it and MgSO4 forms a needlelike crystal.
A crystal of NaCl (table salt)
Epsom salt needle-like crystals
There is additional information in the summary attached to the unit schedule.
Materials for groups of 4 students
1 spoonful of Epsom Salts (MgSO4)
25 mL water and measuring device (syringe or graduated cylinder)
Stirring sticks
Evaporating dishes
Foss trays
LESSON OVERVIEW
Brief planning:
 Read engaging scenario.

Discuss the problem and focus question based on the engaging scenario then record.
TESLA Mixtures and Solutions Lesson 3 – Separating a Salt Solution DRAFT 07/26/13
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
Discuss how to solve the problem then write the prediction.

Students will make a solution of 25 mL of water and the spoonful of Epsom salts.

They will pour a small amount of the solution into evaporating dishes, label and set into
FOSS trays to evaporate. You can use the sun or an incandescent lamp to evaporate the
water quickly.

Students will observe the needle-like crystals and record data in charts.

Making Meaning Conference: guided discussion on writing claims based on evidence
obtained and defining a pure compound, atoms and elements.

Conclusion: writing a report of findings.

Reflection: writing about types of matter: mixtures, solutions, pure compounds.
DAY ONE
ENGAGING SCENARIO
Teacher says:
Clearwater Construction is happy with the separations that you did for them. Now
they have a new problem: they have found an unidentified white solid on their
building site and they are wondering if it is the same as the pure table salt that you
separated from water for them. They would like to hire you to find out. They would
like a report from you in two weeks. What is the problem here?
Teacher’s notes: Students are to think what problem(s) they need to solve for this next
investigation. Solicit ideas for the focus questions from the class and display on the board.

Make a selection of the one that will best solve the problems in the scenario.

Students write CLASS FOCUS QUESTION in their notebooks, if it is different from theirs.

Check notebooks and provide feedback when necessary.
TESLA Mixtures and Solutions Lesson 3 – Separating a Salt Solution DRAFT 07/26/13
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FOCUS QUESTION (discuss by groups, display, record in notebooks)
SUGGESTED CLASS FOCUS QUESTIONS
How can we determine if the unidentified white solid is pure table salt?
Word Wall- Solid: a material with a
fixed shape.
PREDICTION (discuss in groups, record in notebooks)
Teacher’s Notes:
Students write predictions on how to determine if the unidentified white solid is pure table salt.
Remind students that they have to include the word “because” in order to justify their prediction.
Example of a Prediction: (optional format)
I think that we can determine if the white solid is pure table salt by_________________
______________ because__________________.
For example:
I think that we can determine if the white solid is pure table salt by dissolving the solid in water, letting
the water evaporate and looking for the “x” because that is how we figured out that we had salt in the
last lesson.
DAY TWO: PLANNING
Teacher’s Notes and Instructions: Planning how to determine if the
solid is salt.
Have students revisit their work from LE2 and discuss among their group how they will determine
if they have table salt.
Teacher says, “I would like for you to draw how you plan to determine if the white solid is a salt.
Draw a ‘before” and an “after” picture of your plan.’
TESLA Mixtures and Solutions Lesson 3 – Separating a Salt Solution DRAFT 07/26/13
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
Allow them time to discuss and draw. Check around to see if the idea of dissolving,
evaporating and seeing if they get a crystal with an “x” has come up

Make sure they label their pictures and indicate what will happen. Have two or three
groups share with the class what they plan to do

Select those you checked who had dissolving/evaporation/checking for an “x” in their plan
to share so the others can hear and get ideas.
Provide additional help if needed
Chart 1: Determining if unknown salt is table salt.
Water evaporating
Water +
unknown
solution
Heat
source
Do crystals have an
“x”?
The students should also sketch a chart in which they record their data:
Chart 2
Properties of Unknown solid
Substance
Appearance of table salt
after water has
evaporated (from LE2)
Appearance of unknown
after water has
evaporated
Color
Shape
Odor
Texture
Is an “x” visible?
TESLA Mixtures and Solutions Lesson 3 – Separating a Salt Solution DRAFT 07/26/13
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DAY THREE: experiment
Teacher’s notes:
Instruct each group of students to:

Gather epsom salt, water, a cup, a stirring stick and an evaporating dish from the materials
table.

mix 1 spoonful of epsom salt with 25 ml of water.

mix until the epsom salt is no longer visible and the solution is clear. There may be a few
grains of epsom salt on the bottom of the cup, but most will dissolve although it may take a
minute or two of stirring.

Label the evaporating dish with the group name.

Pour the solution into an evaporating dishes labeled with the group name. Leave any
undissolved grains in the cup (if a few go in, it is not the end of the world).

Place the dish in a sunny windowsill out of the way of class activities. Crystals will not
form well if the dishes are jostled or moved.

The length of time that it takes for crystals to form can be as short as a few hours,
depending on the temperature, humidity and surface area of the solution. You should get
crystals by the next day.
TESLA Mixtures and Solutions Lesson 3 – Separating a Salt Solution DRAFT 07/26/13
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DAY FOUR: MAKING MEANING CONFERENCE (Teacher directed)
Give students an opportunity to observe the evaporated epsom salt solutions, and to record their
observations in their charts. If only a few needle-like crystals have appeared, let students look at those
crystals (a magnifying lens can help).
1) Share and display findings.
Remember, this is the conferencing stage. It is preferable that students contribute with their ideas.
Ask students to share the information they have written on their chart and drawings. Replicate the
chart on the board or an overhead to analyze data. If students need to check the information they
wrote on their charts, this is the right time to do it.
2) Looking for patterns from the data charts:
Guide students to analyze the data by asking the following questions:
 How could we tell that we made a solution?
 Did the unknown look like table salt before you dissolved it in water?
 Did the unknown look like table salt when it was dissolved in water?
 Did the unknown look like table salt after the water evaporated?
 Do you think that the unknown is table salt? Why or why not?
Also, at some point, you will need to tell your students about the existence of atoms and elements.
Here is a suggested way to do that:
“Table salt and the needle-like crystals have different properties because they are different pure
compounds, made up of different types of atoms, called elements. All matter is composed of atoms.
Carbon, hydrogen, oxygen and nitrogen are common elements in us and our environment. Table
salt is composed of the elements sodium chloride and the needle-like crystals are composed of the
elements magnesium, sulfur and oxygen.”
[if you want to and have time, you can show the students a periodic table on the web, it is a list of
the elements, or show them a simulation of the difference between the elements at
http://phet.colorado.edu/en/simulation/build-an-atom ]
Word Wall- Atom: the smallest unit
that makes up all matter.
Word Wall- Element: a type of atom.
TESLA Mixtures and Solutions Lesson 3 – Separating a Salt Solution DRAFT 07/26/13
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3) Guide students in writing CLAIMS from the evidence on the data chart.
Examples
CLAIMS
I claim that …..
I know that…..
EVIDENCE
I claim this because…..
I know this because…..
1. The unknown looked like table salt when it
dissolved in water.
I was not able to see the particles of the
unknown or salt in the water.
2. The unknown was a different pure
compound than table salt.
The unknown formed needle-like crystals, not
a crystal with an “x”.
3. The unknown was composed of different
atoms than table salt.*
The unknown formed needle-like crystals ,
not a crystal with an “x”.
* This is not a claim that students would be expected to come up with themselves, but one that is important
to discuss as it addresses the guiding questions.
CLAIMS AND EVIDENCE (record in notebook)
Teacher says
“You are now going to write 3 claims and evidence statements. I want you to look at the guiding
questions and answer them with a claim based on the evidence. Revisit the class data chart in order to
write your claims. Record them on your notebook.” Teacher will go with students individually as they
write their claims and evidence based on the guiding questions.
Example sentence structures:
I claim that ____________________I claim this because __________________.
I know that__________________. I know this because _________.
Share and discuss claims and evidence with the class
Check and provide feedback
TESLA Mixtures and Solutions Lesson 3 – Separating a Salt Solution DRAFT 07/26/13
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DAY FIVE: Conclusion and reflection
CONCLUSION (record in notebooks)
Ask your students to write a 1-2 paragraph report or business letter to the Clearwater Construction
Company telling them how to solve the problem presented in the engaging scenario.
Check and provide feedback
REFLECTION (record in notebooks)
Students will revisit the “Big Idea” and their results. They write a new investigable question
I wonder if……. What about if………What would happen if………..
that is related to the topic covered and “big idea”.
Check and provide feedback
TESLA Mixtures and Solutions Lesson 3 – Separating a Salt Solution DRAFT 07/26/13
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ACHIEVED
PROFICENCY FEEDBACK:
CURRICULUM
This guide is:

to be posted on the board/butcher paper so students know what is expected in
their notebooks

to be an evaluation tool for teachers as students work in their notebooks

to be converted into questions as a student self assessment piece
Suggested PROFICIENCY FEEDBACK GUIDE
MIXTURES AND SOLUTONS
LE 3
S
T
Focus Question
 Question written clearly
 Related to the scenario
Prediction
Two


Related to how to tell if the unknown is
table salt.
uses “because”
Us
Data
1 chart and one diagram
 complete and accurate
 labeled with titles
Claims & Evidence
 3 complete sentences showing
understanding of guided questions
Conclusion
 Grammatically correct
 Describes results
Reflection
 writes one question for further investigation
TESLA Mixtures and Solutions Lesson 3 – Separating a Salt Solution DRAFT 07/26/13
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ENGAGING SCENARIO LESSON 3
Clearwater Construction is happy with
the separations that you did for them.
Now they have a new problem: they
have found an unidentified white solid
on their building site and they are
wondering if it is the same as the pure
table salt that you separated from water
for them. They would like to hire you to
find out. They would like a report from
you in two weeks. What is the problem
here?
TESLA Mixtures and Solutions Lesson 3 – Separating a Salt Solution DRAFT 07/26/13
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Chart 2
Properties of Unknown solid
Substance
Color
Shape
Odor
Texture
Is an “x”
visible?
Appearance
of table salt
after water
has
evaporated
(from LE2)
Appearance
of unknown
after water
has
evaporated
TESLA Mixtures and Solutions Lesson 3 – Separating a Salt Solution DRAFT 07/26/13
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