# Calculate the gap


## 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 poster plan needs 700 labels; 348+175 available.

## Complete new source

An imaginary badge plan needs 650 badges; 287 and 196 available.

## Complete own invitation

A pretend game needs 800 cards; 456+187 available.

## Entry and teach

Use count up to a target or exact subtraction, not subtract each pile from target separately then add gaps.

## Guided instruction

523 available, 177 needed. Invite each relationship before the answer; teach missing facts and name help.

## Id

NEXT18

## 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. Use count up to a target or exact subtraction, not subtract each pile from target separately then add gaps.

2. Model on separate adult paper. 483 available; 650−483=167 needed.

3. Guide a different complete source. A fictional poster plan needs 700 labels; 348+175 available. 523 available, 177 needed.

4. Receive one own attempt. A pretend game needs 800 cards; 456+187 available. Staff reference only: 643 available, 157 needed.

5. Compare available work with: Exact available count and one properly interpreted gap are valid. Choose one follow-up offer; never infer independence from a copied model.

## What to look for

Exact available count and one properly interpreted gap are valid.

## Staff own possibility

643 available, 157 needed.

## Teacher model

483 available; 650−483=167 needed.

## Timing

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

## Title

Calculate the gap