The Toy Car Race
Leo and Sam race toy cars down ramps. Leo's car rolls 180 cm, and Sam's rolls only 20 cm.
Leo says a taller ramp sends a car further. Does this race show it?
Page 1
Science · Grade 3 Science
Chapter 1: Forces and Motion
Change one thing. Write down what you kept the same.
Leo and Sam race toy cars down ramps. Leo's car rolls 180 cm, and Sam's rolls only 20 cm.
Leo says a taller ramp sends a car further. Does this race show it?
Make your guess to turn the page.
Still to come: 7 pages · Words to Know · What We Learned · 4 questions · Explain It in Writing · Ask and Wonder
The idea this lesson is working on — Children use "fair" to mean everyone got a go. In the race both boys had a turn, but the ramp and the floor both changed, so the result cannot say which one mattered. Ana's test changes only the ramp. Ask: what was different between the two runs? If the answer is more than one thing, the test cannot answer the question.
The words scientists use — The thing you change is the independent variable; the thing you measure is the dependent variable; everything held still on purpose is a control variable. Your child does not need the long names yet. Change one, measure one, keep the rest the same is the whole idea.
Repeat each measurement — Do each run three times and compare. If the three are close, the result is reliable. If they are wildly different, something you were not controlling is affecting it. Lesson 5 comes back to this.