Today is rung 10 of 13 on this topic
Percent as a ratio out of a hundred
Can do: Finds percentages, percent increase and decrease, and works backwards from a percentage to the whole.
Why it matters
Percent is the maths a child will actually use most as an adult — discounts, interest, tips, tax, statistics.
What it looks like when it's wobbly
Can find 10% but nothing else; thinks a 20% rise followed by a 20% fall returns to the start.
⏱️ Two-minute check
"What's 15% of 60? A $40 coat has 25% off — what's the price? If 30% is 12, what's the whole?"
Solid looks like: 9, $30, and 40.
The full activity for this topic · 20 minutes
Ten Percent Is Your Friend
- 1Teach the anchor: 10% is dividing by ten. Everything else builds from it.
- 25% is half of that, 15% is 10 plus 5, 20% is 10 doubled.
- 3Work out real sale prices from a catalogue, mentally, then check with a calculator.
- 4Do the reverse: the sale price is $30 after 25% off, what was the original?
- 5Test the intuition trap: 20% up then 20% down, and calculate what actually happens.
If it's too hard
Multiples of 10% only, mentally.
If it's too easy
Compound percentages: two successive discounts, or interest over three years.
Say this
"Start with 10%. Now build the number you actually need out of that."