Sketch a quick box-with-an-arrow-in-and-arrow-out on the IWB with × 3 in the middle. Take three hands-up answers for input 4, then a second round of hands-up for input 7. Five seconds of quiet think-time before any hands go up.

Walk each example aloud, one at a time. On Example 1, point to the 0 → 0 row and say even zero obeys the rule. On Example 2, point along a column and ask 'what's the same on every row?'; the gap of 5 is the rule made visible.

Between Example 2 and Example 3, pause for five seconds and ask the class to name what the + 5 machine did, in one short sentence each. Take two hands-up answers and revoice the better one before opening Example 3. That brief pause keeps the watching class from filling up before the two-step rule lands.

On Example 3, narrate the two steps in order: double it first, then add 1. The interactive shows the × 2 then + 1 path; the reversed-order contrast (+ 1 then × 2, giving 8 instead of 7) sits in the description for pupils to read, so anchor it by saying it aloud: same numbers, different order, different answer. On Example 4, pause on 0.05 → 0.5; this is the place-value-shift moment from earlier in the year. A × 10 machine works on decimals too.

This round is for talking it through together; pupils take turns at the board and the class agrees or corrects out loud.

Bring four pupils up in turn, and give each turn a distinct job so the watching class always has something new to notice:

• Turn 1: a small whole number (e.g. 2 or 3). After it lands, ask the class 'what did the machine do?'; you are looking for the × 3 rule articulated in pupils' own words.
• Turn 2: a bigger whole number (e.g. 12 or 15). Ask 'does the same rule still work?'; the answer (yes) is the durable idea.
• Turn 3: 0. Ask 'what comes out of a × 3 machine when 0 goes in?'; revoice even zero obeys the rule.
• Turn 4: a decimal (0.5 or 1.5). Ask the class to predict first, then check on the machine; anchor back to the place-value-shift idea if needed.

One pupil at the board per challenge, in turn. Read the rule aloud as a class before the first input is typed: 'this machine multiplies by 3'. After each output, the class confirms or corrects out loud, then the next pupil comes up for the next challenge.

Look for pupils slipping on the two-step rule; listen for someone saying 'add 1 first then double' and revoice double first, THEN add 1. The × 10 challenge with decimals (0.5, 1.2, 4, 0.05) is the trickiest of the core bank; anchor it back to the place-value-shift work earlier in the year if anyone wobbles.