Take three hands-up answers, not open call-outs. Give five seconds of quiet think-time before any hands go up. Do not reveal the answer yet — that is the job of the next step. The box starts empty on screen, so nothing is given away.

• □ + 4 = 10 — ask for the missing part before revealing; the whole is 10, one part is 4, so the box is 6. Say take the part you know away from the whole.
• □ + 3 = 8 — same move, box is 5.
• 7 = □ + 2 — the whole (7) is now on the left. Hold out for pupils spotting that it is still whole-take-away-part, so the box is 5.
• □ − 2 = 6 — the trickiest. Show the box-building balance first (slot 3): the box pan is built from 6 and 2 loaded together, so the class SEES the box must hold both parts. Then show the take-away balance (slot 4) and ask the class to name the number the box holds — do not say it first. It is 8 (6 + 2). Point at both pans so the class sees why the box grows.

Work these together at the board — a pupil slides the unknown on each balance while the class agrees or corrects out loud, before anyone confirms the answer.

For each equation, ask what do we know and what are we hunting for? Is the box a part or the whole? before anyone slides the unknown. On 12 = □ + 4 hold out for the class noticing the whole is on the left this time, so the box is 8. On □ − 3 = 5 pause: the box is the whole now, so it must hold both parts put back together (5 + 3) — point at the pan holding the box so the class sees why it gets bigger. Do not say the total before pupils try it. After each level beam, ask a pupil to read the true sentence aloud.

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

Ask before each Check: is the box a part or the whole here? The first three have the box as a part (take away to find it). □ − 3 = 8 has the box as the whole, so it holds both parts put back together (8 + 3) — the last and trickiest. Let pupils reach the total themselves before you confirm it.