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3.4 WATER PROPERTIES
Does water expand or contract when it freezes?Activity Time: 20 minutes
1. Press the piece of clay inside on the center of the bottom of the jar.2. Pour tap water into the jar until it is almost full.3. Add 4 drops of food coloring and stir.4. Lower the straw slowly into the water.5. Push the straw into the clay so it is standing.6. Slowly pour all of the water out of the jar, keeping the water in the straw by placing your finger
on the top.7. Mark the height of the water in the straw with the pen.8. Freeze the jar overnight.9. Measure the change in the height of the ice.
Per Group:Small piece of clay1 small jarBlue food coloring1 permanent marking pen1 spoon1 metric ruler1 straw
• How else can you prove that water expands when frozen?• Design an experiment and share the results with the class.
Complete Assessment 3.4: Does water expand or contract when it freezes?
Background
Directions
Materials
Extension
Assessment
Why does water expand when it’s frozen? Water molecules are attracted to one another and stick together or bond when they get close enough. The molecules have spaces between them and the spaces change depending on their temperature. Liquid molecules are more flexible and can crowd together, making them take up less space or volume. As the temperature gets colder, the molecules form a hexagonal structure that is not flexible and takes up more space than the same number of liquid molecules.
Vocabulary
Expansion: growth or spreading out.
Liquid: a substance that flows whose shape can be changed but not its volume.
Volume: the size of a three-dimensional space enclosed within or occupied by an object.
Related ActivitiesWhy does ice float? (3.2)Why does this magic trick work? (3.5)
ALIGNMENT TO NGSS:Scientific and Engineering Practices•Asking questions•Planning and carrying out
investigations•Constructing explanations•Engaging in argument from
evidence•Obtaining, evaluating, and
communicating informationCrosscutting Concepts•Cause and effect•Stability and change
Disciplinary Core Ideas•K-5: PS1.A•6-8: PS1.A
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