Topic 3 How to investigate a force like a scientist — what needs James (29)

1. [Investigating unequal forces: two pulls on a box](../g5/topic03/index.html#/lesson/Lesson 1 (Investigating unequal forces: two pulls on a box)/script)

(FOR5-024) — one box, a rope each side; equal pulls, the box stays still (Grade 3's balanced-forces sentence recalled); Desmond joins Delia's rope and the box moves toward the two of them and speeds up; the same change the other way; the class's results table; "change one thing at a time and watch". Video 149 words · article 356 · 9 quiz items · 5 figures.

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2. [Say what you expect before you test](../g5/topic03/index.html#/lesson/Lesson 2 (Say what you expect before you test)/script)

(SR5-001) — Delia's ramp; Desmond's "something will happen" against Delia's "the car will roll farther from the steeper ramp", judged by one question: can the test show whether it was right?; three more sentences in a table; "prediction" coined last; a wrong prediction still teaches you something. Video 149 words · article 302 · 9 quiz items · 5 figures.

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3. [How to plan the whole fair test](../g5/topic03/index.html#/lesson/Lesson 3 (How to plan the whole fair test)/script)

(SR5-002) — Grade 4's fair-test sentence recalled, then the four lines written on the board for the ramp test (the question, the one thing we change, what we keep the same, what we measure); a push added to one ramp makes two changes, and taken out again makes one; Grade 4's rule sentences word for word. Video 147 words · article 388 · 10 quiz items · 5 figures.

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4. [Why you run a test more than once](../g5/topic03/index.html#/lesson/Lesson 4 (Why you run a test more than once)/script)

(SR5-003) — 95, 78 and 84 centimeters from the same ramp; nobody made a mistake; one roll from each ramp (95 against 92) would point the wrong way; all three rolls together show the steeper ramp usually rolls farther; Cyrus's "one roll is all we need" recapped and contradicted after the evidence. Video 150 words · article 328 · 8 quiz items · 4 figures.

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5. [Design a force experiment: the plan](../g5/topic03/index.html#/lesson/Lesson 5 (Design a force experiment: the plan)/script)

(FOR5-025, part 1) — Desmond's rubber band on two pegs pushes a toy car along a board; his question is about a force; he changes how far the band is stretched (5, 10, 15 centimeters), keeps the car, band, board and floor the same, measures how far the car rolls, predicts, and plans three runs each. Video 150 words · article 298 · 8 quiz items · 4 figures.

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6. [Design a force experiment: carry it out](../g5/topic03/index.html#/lesson/Lesson 5b (Design a force experiment: carry it out)/script)

(FOR5-025, part 2) — three runs at each stretch, every distance in a table with the unit in the top row; all three runs read together; the result compared with the prediction; the band stretched farther pushes the car harder, and the stronger force makes the bigger change (Grade 3's words). Video 150 words · article 250 · 8 quiz items · 4 figures.

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1. Should FOR5-024's investigation read spring scales in newtons, or compare the two pulls by who pulls and by the arrows' lengths, as built?

The register's example is "dragging a box with one spring scale, then with two pulling together", and its decisions text says FOR5-022..025 "perform with spring-scale measurements"; the atom's cross note says "read a labelled scale" is a grade 3 maths mirror.

No Grade 3-5 atom coins the newton, and every number in the course carries its unit, so a drawn scale would show either a bare number or a unit nobody has taught.

As built, the class changes who pulls, the box's motion is the thing watched, and the arrows' lengths (Grade 3's register) carry the comparison; adding scales is one instrument drawing, two article lines and three items, and the newton can wait for grades 6-8.

My recommendation: as built — no spring scale, no newton

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