# Borrow a friendly number, then put it back ## Access Show, draw, type, sign, use your usual communication or direct an agreeing helper. Choose quiet/private work, switch a route, pause, pass or finish. One useful part is enough. A helper can read the exact words or scribe your choices; supplying an operation, count, regrouping or reason is mathematical help and is named. No speed, neatness, speech, handling or device requirement. ## Adult model 398 + 267 = 400 + 267 − 2 = 665. We added two extra in the friendly-number step, so remove two from 667. About 400 + 300 = 700 is an estimate, not this exact calculation. ## Child direction Would moving to a nearby round number make this job easier? Pick one route. Show what the numbers mean, try a way, then check one result. You can stop after a useful part. ## Common tangle the adjustment goes the wrong way; check the roles and equivalent quantities, rather than memorising a printed answer. ## Day 53 ## Different guided practice For fictional prompt cards, 497 + 186 = 500 + 186 − 3 = 683. Contrast the wrong 686: it counts the three extra cards. Invite a different check: 497 + 180 + 6. ## Check and teach the entry relationship Ask why 39 + 12 can be worked as 40 + 12 − 1. Model with a labelled extra mark if needed. Teach the compensation before rounding two large inputs. ## Hook Would moving to a nearby round number make this job easier? ## Materials Broad paper, labelled place-value/part-whole/number-line alternatives as suitable; optional familiar safe counters; usual communication. No hundreds of loose marks, purchases or physical handling required. Keep adult model and own work separate. ## Next ordinary teaching If the adjustment goes the wrong way, compare 19 + 6 with 20 + 6 − 1 using marks. Guide 29 + 14, then invite 49 + 17 = 66. ## Complete fictional source An invented sticker design has 398 blue stickers and 267 plain stickers. Find the exact total. ## One own invitation Work 299 + 146 exactly using a friendly number, and name the adjustment. ## Partial curriculum opportunity 1. AC9M4N06 2. AC9M4N07 partial ## Purpose Use exact compensation and distinguish it from estimation. ## Routes 1. ### Access Show, draw, type, sign, use your usual communication or direct an agreeing helper. Choose quiet/private work, switch a route, pause, pass or finish. One useful part is enough. A helper can read the exact words or scribe your choices; supplying an operation, count, regrouping or reason is mathematical help and is named. No speed, neatness, speech, handling or device requirement. ### Complete task An invented puzzle tray joins 49 and 27 pieces. Use fifty carefully. ### Entry or access Draw the one added extra separately. ### Id A ### Title Puzzle pieces ### After own work: adult practice possibility 76: 50 + 27 − 1. 2. ### Access Show, draw, type, sign, use your usual communication or direct an agreeing helper. Choose quiet/private work, switch a route, pause, pass or finish. One useful part is enough. A helper can read the exact words or scribe your choices; supplying an operation, count, regrouping or reason is mathematical help and is named. No speed, neatness, speech, handling or device requirement. ### Complete task Find 398 + 267 and compare compensation with chunks. ### Entry or access Explain which quantity was changed. ### Id B ### Title Sticker plan ### After own work: adult practice possibility 665 exactly; 700 is a coarse estimate. 3. ### Access Show, draw, type, sign, use your usual communication or direct an agreeing helper. Choose quiet/private work, switch a route, pause, pass or finish. One useful part is enough. A helper can read the exact words or scribe your choices; supplying an operation, count, regrouping or reason is mathematical help and is named. No speed, neatness, speech, handling or device requirement. ### Complete task An imaginary exhibit game counts 1998 + 367 slips. Compare exact compensation and a nearest-hundred estimate. ### Entry or access This fictional game is not a museum programme or attendance fact. ### Id C ### Title Museum-copy game ### After own work: adult practice possibility 2365 exact; 2000 + 400 ≈ 2400, 35 above exact. ## Session stages 1. ### Instruction Would moving to a nearby round number make this job easier? Read the source. Ask what the numbers count and the wanted quantity. Ask why 39 + 12 can be worked as 40 + 12 − 1. Model with a labelled extra mark if needed. Teach the compensation before rounding two large inputs. ### Minutes suggestion 5 ### Stage Meet the job 2. ### Instruction 398 + 267 = 400 + 267 − 2 = 665. We added two extra in the friendly-number step, so remove two from 667. About 400 + 300 = 700 is an estimate, not this exact calculation. Show on separate adult paper. Pause after one transformation; invite explanation before showing the next. ### Minutes suggestion 10 ### Stage Teach one relationship 3. ### Instruction For fictional prompt cards, 497 + 186 = 500 + 186 − 3 = 683. Contrast the wrong 686: it counts the three extra cards. Invite a different check: 497 + 180 + 6. Offer one complete route below, not all three as a quota. Let the learner select a representation and pause or switch. ### Minutes suggestion 15 ### Stage Guide then choose 4. ### Instruction Work 299 + 146 exactly using a friendly number, and name the adjustment. Receive an available response before staff key. If the adjustment goes the wrong way, compare 19 + 6 with 20 + 6 − 1 using marks. Guide 29 + 14, then invite 49 + 17 = 66. ### Minutes suggestion 5 ### Stage Receive and choose tomorrow ## What to look for The nearby number, compensating adjustment and exact result are linked; rounding alone is not an exact proof. ## After own work: staff possibility 445: 300 + 146 − 1; the added extra one is removed. ## Status Proposed 35-minute shape, unpiloted and freely reorderable; resource day not school calendar requirement. ## Title Borrow a friendly number, then put it back