Do not send this whole bank or recipe/aid-data to learners. Accept correct alternative reasoning and usual communication; physical presentation, speed and amount written are not maths components.
e-first · Estimate and check
Full supplied source: MODEL collection: 5 complete groups of 20 pieces and 8 loose pieces. Two fictional material batches are 317 and 268 pieces. Stock is 600 pieces. A ticket reports the combined batches as 58 pieces. No real class count, purchase or event is asserted.
Q1 · Estimate the collection using a known group. Explain your clue; keep an estimate different from an exact count.
Worked/acceptable response: Example about 110 or a justified range around 108, anchored to 5×20 plus a small loose group. Exact count 108 is not required for the estimate; don't relabel an exact computation as an independent estimate.
Component: Known-group estimate and uncertainty
Evidence: independently shown / shown with named cue / partial / not observed. A correct supplied result with adult computation is supported result, not independent reasoning.
Specific unrelated next teaching: Estimate a new collection with a clearly known small group.
Q2 · Before exact addition, give a useful estimate of the two batches and explain a benchmark.
Worked/acceptable response: Example benchmark 300 + 300 = 600, or another defensible useful estimate explained before the exact calculation; an estimate is not a guaranteed interval.
Component: Purposeful benchmark before exact result
Evidence: independently shown / shown with named cue / partial / not observed. A correct supplied result with adult computation is supported result, not independent reasoning.
Specific unrelated next teaching: Compare a new sum with two different useful benchmarks.
Q3 · Calculate the exact combined batches. Is stock enough, and what is left?
Worked/acceptable response: 317 + 268 = 585; stock 600 is enough with 15 pieces left.
Component: Exact additive/context/remaining quantity
Evidence: independently shown / shown with named cue / partial / not observed. A correct supplied result with adult computation is supported result, not independent reasoning.
Specific unrelated next teaching: Represent a new total and stock using grouped place value.
Q4 · Explain why 58 needs checking. Use a connected inverse check for your own exact total.
Worked/acceptable response: Two positive hundreds cannot total 58; 585 − 268 = 317 (or 585 − 317 = 268) connects the exact parts. Rough scale alone does not prove every digit.
Component: Reasonableness and connected inverse
Evidence: independently shown / shown with named cue / partial / not observed. A correct supplied result with adult computation is supported result, not independent reasoning.
Specific unrelated next teaching: Use an unrelated subtle digit error requiring an exact inverse check.