Give five seconds of quiet think-time before any hands go up. Take two or three hands-up answers, not open call-outs. Do not confirm the answer yet — the next step will settle it.

Listen for pupils who count up from 4 to 9 versus pupils who reason 'take the 4 away from both sides'. Both are welcome now; the second is the idea the lesson builds on.

• x + 4 = 9 — ask what has to come off the left pan to leave the bag alone, then point out the same 4 must come off the right too, or the beam tips.
• x − 3 = 6 — the trap: pupils want to take away again. Point at the short bag on screen and hold out for the idea that it has already lost 3, so we add 3 back to both sides to fill it up.
• 3x = 15 — here we share, not subtract. Say 'three equal bags, so split each pan into three fair groups'. The line 'do the same to both sides' still holds — we divide both pans by 3.

Do not read the working aloud line by line — point at each pan and let the class say what has to happen before you reveal it.

Talk this one through together — the class names the move aloud, one pupil works the slider at the board, and the class agrees or corrects out loud before the pupil presses Check.

Before touching the slider, ask the class to name the move: take 6 off both / add 2 to both / share into 4 equal groups. Then a pupil slides the unknown to the value that levels the beam and presses Check. Watch for the x − 2 = 5 one — the class must add, not subtract; if the beam tips the wrong way, that is the teaching moment. Revoice a strong answer: so whatever we do to one pan we must do to the other, or it stops balancing.

This is the practice round — pupils take turns at the board, check each answer, and the class confirms before moving on. Keep the board work brisk rather than over-explaining.

Use the Check tick as part of the narration: yes — that's it. For each round the whole class predicts and calls out; the pupil at the board slides the value and presses Check. As a talking point after the whole-number set, ask the class what would happen with a bag like 2x = 9 — two equal bags sharing 9 could not each be a whole number, so the bag would hold four and a half. This shows the class that solutions can be decimals, without relying on the slider landing on a fraction live.