Term 1 Week 7 · Percentage increase and decrease · CG Quarter 1, competency 7
| # | The misconception | Where it shows | What to do |
|---|---|---|---|
| 1 | Up p% then down p% returns to the start | §B, by design | Nothing until §D. It must be disproved by the learner's own arithmetic |
| 2 | The second percentage is of the original | §C.1 — learner computes 20% of 100 twice | "What does it cost right now, before it goes down?" Never give the base; ask for it |
| 3 | Percentages can be added and subtracted directly | "up 20 and down 20 is zero" | Show the two peso amounts. 20 and 24 do not cancel |
| 4 | 20% means divide by 20 | §A | 20% = 20 per hundred = ⅕. Anchor on 10% first |
| 5 | The answer depends on the order | §C.3 | Compute both orders. They agree — and that is Day 2's hook |
| 6 | This is a trick / the shop is cheating | §D | No trick: both discounts are honest. The arithmetic simply is not symmetric. Worth saying plainly |
| 7 | It only happens with 20% | §C.4 row 5 | 50% up then 50% down loses a quarter. Bigger percentage, bigger loss |