Compare the Weight of a Specified Quantity of Matter Before and After It Undergoes Melting

Topic: Properties of matter, physical change and chemical reaction
Root Question: What are the properties of matter and how does it change?
Standard addressed:5.1 Fifth grade matter: The weight of an object is always equal to the sum of its parts, regardless of how it is assembled. In a chemical reaction or physical change matter is neither created nor destroyed. When two or more materials are combined, either a chemical reaction or physical change may occur. Chemical reactions are often indicated when materials give off heat or cool as they take in heat, give off light, give off gas, or change colors. In a chemical reaction, materials are changed into new substances. In a physical change a new substance is not formed. / Indicators addressed: Compare the total weight of an object to the weight of its individual parts after being disassembled.

Compare the weight of a specified quantity of matter before and after it undergoes melting or freezing.
Investigate the results of the combined weights of a liquid and a solid after the solid has been dissolved and then recovered from the liquid (e.g., salt dissolved in water then water evaporated).
Investigate chemical reactions in which the total weight of the materials before and after reaction is the same (e.g., cream and vinegar before and after mixing, borax and glue mixed to make a new substance).

Language objective: Reading Informational Text Standard 1
Quote accurately from a text when explaining what the text says explicitly and when drawing inferences from the text.
Standard 2
Draw on information from multiple print or digital sources, demonstrating the ability to locate an answer to a question quickly or to solve a problem efficiently.
Writing Standard 2
Write informative/explanatory texts to examine a topic and convey ideas and information clearly. / Content Objective: Objective 1
Describe that matter is neither created nor destroyed even though it may undergo change.
Intended Learning Outcomes:
Use Science Process and Thinking Skills

Observe simple objects, patterns, and events and report their observations.
Sort and sequence data according to criteria given.
Given the appropriate instrument, measure length, temperature, volume, and mass in metric units as specified.
Compare things, processes, and events.
Use classification systems.
Plan and conduct simple experiments.
Formulate simple research questions.
Predict results of investigations based on prior data.
Use data to construct a reasonable conclusion.

Math overlap: Write and interpret numerical expressions.
Read, write, and compare decimals to thousandths. / In summative assessments, students should be able to

State the weight of the water produced from melting when given the weight of an ice cube. Explain how they know this is true.
State the weight of the ice formed when a given weight of water is frozen. Explain how they know this is true.
Determine the weight of a missing piece when given the weight of the whole and the weight of one part (e.g., the weight of a crayon taken from a box when weighing first the box, and then the box without one crayon).
Explain what happens to the weight of a solid, such as sugar, before and after being dissolved in water. Tell what the weight of the solid would be after letting the water evaporate. Explain why they know this.
Describe why the weight of a mixture of vinegar and milk will weigh the same as the sum of its parts even though a chemical reaction takes place.
Describe why the weight of a mixture of vinegar and baking soda may have a smaller weight after mixing.

Scientific/Engineering Processes emphasized:
Chemical and physical change / Cross-cutting concepts:
Cause and Effect - Events have causes, sometimes simple, sometimes multifaceted. A major activity of science is investigating and explaining causal relationships and the mechanisms by which they are mediated. Such mechanisms can then be tested across given contexts and used to predict and explain events in new contexts.
The Lesson Plan
Students will. . . / Materials/Handouts

Students build a simple object from Legos. Weigh the object.
Ask students to predict the sum of the weight of the Legos if we weighed them separately. Students break apart their object and weigh the individual bricks, add the sums together and determine if the amounts are equal or unequal. Remind students that a small difference (<3 grams) may be the result of low scale accuracy.
Students weigh an ice cube in a cup covered with plastic wrap, write down their hypothesis as to its weight once it melts, and set it aside to melt.
Wearing safety goggles students weigh milk and vinegar separately, then stir and weigh the resultant substances. They record and compare the weights.
Students measure and mix vinegar and baking soda in two ways: first letting the resultant gas escape, second trapping the gas in a balloon. They compare the weight results to see that gases have weight. Remind them that a gas is matter and therefore has mass and weight.
Go back to the ice cubes and finish the experiment by weighing the melted ice. Did it happen as students hypothesized?
Ask if all materials act this way. Can they come up with a rule to explain all their results? Introduce the vocabulary “created” and “destroyed.” Students defend their premise in a short written paragraph using evidence from the experiment and using the vocabulary words – chemical reaction, physical change, create, destroy.
Working in groups students read and discuss the material in the OER resource book on physical change and chemical reaction. Together they add some of each kind of changes to their worksheet.
The physical changes listed in the chart are designed to be used either of two ways. As a hands-on activity, student groups can be assigned to try one of the physical changes and report their results. Or students can read and consider the changes and determine if there is a reasonable way to reverse them. Help them understand that taping something back together is not the same as it being reversible. Instead, if your group is ready, you can opt to have students design their own experiment that creates a physical change. They can present their findings to the class and explain why it is or is not reversible.
The table of mixtures is intended for student groups. Depending on your group and available materials you may choose to use them as teacher demonstration pieces with student help. Please be sure to use goggles for these experiments. Once again, if your group is ready, you may choose to have students select their own materials and mix them to determine whether the results are a physical or chemical change.
When the worksheet is complete students will review what they know in two ways. The summative assessment includes a fill-in piece and a constructed response piece. Students should be encouraged to use their worksheets and the OER resources to provide evidence for their answers on the constructed response piece.

Chemical/physical worksheet
Suggest exit ticket questions
Matter Unit Test
OER 5th grade resource book available here:
small plastic cups
plastic wrap or
zip top baggies
ice cubes
small bottles such as plastic water bottles or small neck glass bottles or
graduated cylinders
10” balloons (or about 10”)
baking soda
vinegar
powdered or fresh milk
safety goggles for each student
scale
Legos – 7 for each group
measuring cups, spoons or graduated cylinders that measure in milliliters
salt
iron filings
magnet
carrot
plastic knife
dirt
small hard candy
glue
calcium chloride
hydrogen peroxide
yeast
lemon juice
cabbage juice* or powdered indicator available here:
steel wool (available at home improvement stores)
acetone (nail polish remover)
Styrofoam packing peanuts
borax (available in laundry aisle)
white glue (not “school” glue)
plastic spoons or other stirrers

* To make cabbage juice, cut up and boil red cabbage in water. Let cool and strain. Juice should be refrigerated and can be frozen.
In formative assessments, I am looking for. . .
Formative assessments for this activity will include teacher observation of participation in group activities, answers to questions on worksheet, and exit tickets for each session. Material in the worksheet will take between 3 and 4 sessions of one hour each. Suggested exit ticket questions are provided.
In summative assessments, I am evaluating. . .
Students understand that matter is neither created nor destroyed.
Students can predict the weight of the whole when given the weights of the addends, i.e., the materials being joined together.
Students can use informational text and their own experiences to provide evidence to support their understanding of the processes of chemical reaction and physical change.
Students can make observations about the outcomes of experiments and explain what caused them (cause and effect).
Students are developing an emerging sense of the difference between chemical changes (reactions) and physical changes. Students can state whether a physical change can be easily reversed.
Content support….
Matter is neither created nor destroyed. Even when burned, the molecules in the materials that are consumed simply change into something else. The products’ combined weights will be the same as the original material.
More on matter’s properties here:
A physical change in matter is a change where the substances involved do not change. These changes can take several forms. For example, when water changes to ice a physical change in state of matter has occurred. The water did not become something else, it just became colder. Likewise, when a piece of paper or a carrot are cut, the resulting pieces are still paper or carrot. The substance remains the same. The shape, size, or appearance has changed. When a solid is dissolved into a liquid, often there is no change in the substances. For example, when making punch, sugar and flavoring are dissolved in water. We can still taste the sugar and flavoring and the water is still present. We can even let the water evaporate to recover the sugar and flavoring.
A chemical change or chemical reaction occurs when two or more substances are mixed together and create an entirely new substance or substances. The materials mixed together are called reactants. The substances created this way are called a products. Products can be solids, liquids, or gases. Generally, chemical reactions cause unexpected results. For example, when mixing baking soda (a solid) and vinegar (a liquid) a gas is produced. Neither the liquid nor the solid was heated enough to produce a gas. This gas is an unexpected result. Unusual changes in color are also a sign of a chemical reaction. Purple cabbage juice added to lemon juice will not produce a brownish liquid as one might expect when mixing something purple with something yellow. Instead it creates a pink product. And when glue is added to water and borax, the product is a rubbery solid, not the soupy glue you might expect. Other examples of unexpected results are a change in heat or cold, a change that creates light, or a change in energy that causes an explosion (think fireworks).
Additional Resources for Students and Teachers:
Information on conservation of matter. Teacher information
Student information and quiz
Teacher and student video on matter
Bill Nye Phases of Matter – available through UIMC eMedia or online at YouTube For students but good for teachers, too.
Online experiment on states of matter
Quiz on physical and chemical change
“Hunting the Elements” NOVA video for teachers or excerpted for students.
short video information on different elements. Interesting, but above grade level
Sci-ber Text for matter on UEN

Suggested materials: digital scale, safety glasses or goggles, thermometers, graduated cylinders, small bottles with caps for table teams