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3. Friction Lab
Relationship to big idea
Contribution to student understanding
Remind students of the definition of "variable" - something that can change each time an experiment is done. In this experiment, students will examine the effects of several variables on the force needed to pull a baby shoe:
Tell students the unit used to measure force is called a Newton, abbreviated N. The unit is named after Sir Isaac Newton, an important scientist we will learn more about later.
[After students complete the lab, explain "friction" as a force that stops or makes it harder for two things to slide past each other. Distribute sandpaper - have students pull two pieces past each other. Use rough surface of sandpaper as an analogy.]
Check for understanding
Students discuss results and group variables according to whether they make pulling easier or harder.
Science for social justice: Many of my students are from large families and have young family members. They can relate to choosing baby shoes that are unlikely to slip and therefore safe for a baby to wear. The activity uses a familiar context to promote understanding of the abstract concept of friction.
Cooperative learning: Group members are assigned roles (materials manager, data recorder, tester, executive) which rotate with each test. Groups work on demonstrating cooperative behaviors (take turns, use each other's names, encourage everyone to participate)
Productive questioning: As groups work, teacher asks students reasoning questions. (What have you noticed about pulling shoes over carpet? How many Newtons of force does it take to pull shoes on the floor? How is adding more weight to the shoe like pulling it over carpet? What would happen if we took weight out of the shoe? Why do you think it's harder to pull the sneaker than the smooth-soled suede boot?)