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
-
AC9M4N06
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AC9M4N07 partial
Purpose
Use exact compensation and distinguish it from estimation.
Routes
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.
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.
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
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
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
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
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