# A zero bridge


## Access

Read or sign the exact source and prompts neutrally, enlarge them, or scribe the learner’s chosen words. A figure, operation, regrouping, equation role or check supplied by an adult is mathematical help and is recorded as such. Show, draw, type, sign or use usual communication. One component can be enough; pause/pass/finish are choices. Four own spaces are genuinely empty. Models, criteria and next lessons stay on separate staff pages.

## Complete different guided source

A fictional robot kit starts 602 cards, uses 247.

## Complete new source

An imagined print game starts 503 slips and uses 178.

## Complete own invitation

A pretend mask drawer starts 801 labels, uses 356.

## Entry and teach

Teach 102−38=64 by trading a hundred then a ten.

## Guided instruction

355; 5 hundreds 9 tens 12 ones−2 hundreds 4 tens 7 ones. Invite each relationship before the answer; teach missing facts and name help.

## Id

NEXT06

## Materials

Broad paper/empty bar or line/place-value headings as useful; usual communication; no actual stock/handling/purchase.

## Observe and follow up

Receive one available own relationship before staff possibility. If it matches criterion, offer another small new context later; this is not automatic mastery. If not, return to the entry relationship and fade one hint. Record the actual mathematical help. If access/time is not available, change access or sitting rather than marking wrong.

## Relationship to check

Teach the observed missing relationship in a new ordinary domain; not an answer repetition or further held item.

## Session sequence


1. Read the new source and name units/wanted quantity. Teach 102−38=64 by trading a hundred then a ten.

2. Model on separate adult paper. 503=4 hundreds 9 tens 13 ones; minus 1 hundred 7 tens 8 ones=325.

3. Guide a different complete source. A fictional robot kit starts 602 cards, uses 247. 355; 5 hundreds 9 tens 12 ones−2 hundreds 4 tens 7 ones.

4. Receive one own attempt. A pretend mask drawer starts 801 labels, uses 356. Staff reference only: 445; 7 hundreds 9 tens 11 ones minus 3 hundreds 5 tens 6 ones.

5. Compare available work with: Regrouping across zero retains all starting units and produces a valid difference. Choose one follow-up offer; never infer independence from a copied model.

## What to look for

Regrouping across zero retains all starting units and produces a valid difference.

## Staff own possibility

445; 7 hundreds 9 tens 11 ones minus 3 hundreds 5 tens 6 ones.

## Teacher model

503=4 hundreds 9 tens 13 ones; minus 1 hundred 7 tens 8 ones=325.

## Timing

An adjustable 10–20 minute ordinary lesson, unpiloted; split/stop after one useful part.

## Title

A zero bridge