Day 14 · A line can mislead | Year 4 Maths · T1 W3–4

Code: AC9M4N01 (partial). Goal: test scale, equal spacing and decimal labels before trusting a number-line claim. Prepare: one deliberately uneven teacher line and a correct equal-spaced line; two marker tokens.

Invite · 2 min. Display five spaces drawn with noticeably different lengths between 0 and 1 but labelled 0, 0.2, 0.4, 0.6, 0.8, 1 as if equal. Ask what would have to be fixed before calling this an equal scale. Focus on equal spacing.
Model · 5 min. On a correct 0.00–0.10 ten-gap zoom, show that 0.07 is seventh hundredth tick. On a separate 0–1 ten-gap line, 0.7 is seventh tenth tick. They are not the same point; 0.70 > 0.07. Mark the first line's endpoints and gap size.
Guided · 6 min. Audit a claim that 0.43 > 0.5 because 43 is greater than 5. Rename 0.5 = 0.50; on matched same-whole hundred-grid/line 0.43 < 0.50 by 7 hundredths. Repair the uneven line by marking equal gaps.
Choice · 6 min. Select D14-A/B/C and keep the incorrect first claim visible beside the correction. The learner explains which feature—place or scale—caused the error.
Exit · 4 min. Compare 0.49 with 0.5 = 0.50; 0.49 < 0.50 by one hundredth. If a learner thinks 49 > 5, match decimal places first.
Note · 2 min. Record whether the error is scale, endpoint, gap-count or tenths/hundredths value; use the matched repair in staff key.

Access/home/extension: Use tactile equal tiles instead of relying on visually judged line lengths. No real measurement or personal score is required. Extension: write a false scale claim for a partner to diagnose without changing the number values.