# C11 · Interval walk on paper

## Boundary

Diagram reading is not measurement of an actual rock or scaled instrument operation.

## Complete source

Fictional tape diagram has zero, 1, 2, 3, 4 cm marks and a paper label spanning zero to four. Five tick marks bound four intervals.

## Id

C11

## Invitation

Use large paper steps or pointing to show the measured length.

## Next try

Measure a different actual paper strip with a familiar ruler if supervised and wanted; keep its own record.

## Ordinary possible response

The span is 4 cm: I count the intervals from zero, not all five marks.

## Title

Interval walk on paper