Teacher: For a learner who did not get there with <code>worksheet.html</code>. This is not a shorter version — it is built on one habit: writing every force as a complete sentence naming both objects, before any arrow is drawn. Four tasks, big boxes, and a worked example above each.
1 Two objects, always — rewrite each short phrase as a full sentence
Worked example:"There is a push of 10 N." → "The hand pushes the box with 10 N, to the right." Who is pushing, what is being pushed, which way.
The short phrase
The full sentence
There is a pull on the rope.
A force of 5 N acts.
Gravity acts on the ball.
2 Swap them round — the partner is the same sentence backwards
Worked example:"The hand pushes the box." Swap the two names: "The box pushes the hand." Same size, opposite direction. That is the partner, every time.
The force
Swap the names
The foot pushes the ground
The bat hits the ball
The Earth pulls the book
3 Which object does it act on — write only the object, one word
Worked example:"The table pushes the book up." Which object is being pushed? The book. That is the object the force acts on.
The force
It acts ON
The Earth pulls the book down
The table pushes the book up
The book pushes the table down
The book pulls the Earth up
Look at your four answers. <b>Two say book.</b> Those two are on the same object, so they are not a pair.
4 Now decide — use your answers from task 3
Worked example: If the two forces act on the same object → not an action–reaction pair. If they act on two different objects → yes, a pair.
A pair, because…
Not a pair, because…
This is where <code>worksheet.html</code> Section B begins. When a learner can do task 4 unaided, the bridge is finished.
Answer key — screen only, not printed.
<b>1</b> · varies; every answer must name two objects and a direction. | <b>2</b> · the ground pushes the foot · the ball pushes the bat · the book pulls the Earth. | <b>3</b> · book · book · table · Earth. | <b>4</b> · pair: forces on two different objects, e.g. book and table. Not a pair: both on the book.<br><b>Task 3 is the one that does the work.</b> A learner who writes the object for every force will never again call the book's weight and the table's push a pair.