Day 11 · Distribute to every partYear 8 Maths · T1 W3–4 · Day 11 lesson

Codes: AC9M8A01. Goal: expand a linear expression and prove equivalence with a substitution. Prepare: expression tiles or labelled text strips.

1. Launch · 2 min. A fictional maker prepares three identical packs, each with x plain cards and 4 marker cards. Ask what 3(x+4) counts. Name x before operating.
2. Model · 5 min. Draw three groups of x+4. Count x+x+x+4+4+4=3x+12. State the distributive property: 3(x+4)=3x+12. At x=2, both give 18 cards. An example check supports, but does not alone prove all values; the grouping explains the identity.
3. Guided · 6 min. With four groups, expand 4(y+2)=4y+8; substitute y=3: both 20. Read each multiplication sign aloud if useful.
4. Practice · 6 min. Offer D11-A/B/C from the choice sheet: tile array, spoken script or error hunt. Require distribution to both terms and a new-value check.
5. Exit · 4 min. Correct 2(z+6)=2z+6 and show at z=1: original 14 versus wrong 8; corrected 2z+12=14.
6. Note · 2 min. Record property and substitution separately. If only one term was multiplied, return to two physical groups, not a speed drill.

Later: Day11 extra uses another invented pack, with no device needed.