Solids & Liquids
Investigation 4
Part 3
Toothpaste Investigation
Students apply their knowledge of solids and liquids to determine if toothpaste is solid or liquid. (from the FOSS teacher guide, 2002 edition)
Students will add water to toothpaste and see what happens when the toothpaste is left to settle in the bottle and when the toothpaste is mixed by shaking in the water.
3. Lesson set up and Management
- PC01 1.1.1 Use properties to sort natural and manufactured materials and objects, for example, size, weight, shape, color, texture, and hardness.
- PC02 1.1.4 Observe and examine physical properties of earth materials such as rocks and soil, water (as liquid, solid, and vapor) and the gases of the atmosphere.
- SI01 1.2.5 Know that matter can undergo changes of state such as evaporation, condensation, or freezing and thawing.
- IP01 2.1.1 Ask questions about objects, organisms, and events in the environment.
- IP02 2.1.2 Plan and conduct simple investigations using appropriate tools, measures, and safety rules.
- IP03 2.1.3 Use data to construct reasonable explanation.
- IP05 2.1.5 Record and report observations, explanations, and conclusions using oral and written expression.
- IP07 2.2.2 Design and test a solution to a problem.
- Some materials have properties of both solids and liquids.
- Scientists test materials in many ways in order to compare them to what is known.
3. Lesson set up and Management
* This investigation takes three sessions over a week-long period. Plan ahead on timing.*
Materials:
- Copy Student Sheet #30, Investigating Toothpaste.
- Chart paper and pens/markers
- Assessment Checklist
- Copies of Home/School Connection Sheet #42 for homework.
Student Management:
This investigation will take two days. Plan ahead and try the experiment ahead of time. It is important that students do not shake the bottles at first. Remind them of this.
The point of this part is to get the students to design an investigation. Encourage ideas until someone says to put the toothpaste in water. Develop that idea into a hypothesis. Observe the toothpaste without shaking the bottle and with shaking the bottle. Have a place prepared to put the toothpaste until the next day.
This is a good opportunity to encourage students to use a WASL-like format for developing their hypotheses. Encourage students to explain their reasoning behind their hypotheses. Because there is no manipulated or responding variable in this investigation, they will not be able to develop a full problem and hypothesis, but they can use the WASL "if/then/because" language. For example, "If toothpaste flows and always settles with a level surface (does not form piles), then toothpaste is a liquid because small solids can flow but can stay in piles without settling to a level surface."
WRAP-UP/CLOSING
- Make entries to the "What We Learned" Chart and update the "Questions I Have" Chart.
ASSESSMENT: Conduct 30-second interviews and make checks on the Assessment Checklist.
Math Support:
Make a T-Chart with the headings "Solid" and "Liquid". Have students give evidence supporting whether they believe toothpaste is a solid or a liquid, and record the evidence students give under the correct heading.