Today is rung 3 of 8 on this topic
Negative numbers and the number line
Can do: Orders, adds and subtracts integers, and uses absolute value sensibly.
Why it matters
Negatives are the first numbers with no physical objects behind them, and a shaky grip here breaks algebra permanently.
What it looks like when it's wobbly
Thinks −8 is bigger than −3 because 8 is bigger, and treats subtracting a negative as arbitrary.
⏱️ Two-minute check
"Which is bigger, −8 or −3? What's −5 + 8? What's 3 − (−4)?"
Solid looks like: −3, 3, and 7 with some reasoning.
The full activity for this topic · 20 minutes
Temperature and Bank Balance
- 1Use a vertical number line like a thermometer. Colder is lower, and lower is smaller.
- 2Ask real questions: it was −5 and rose 8 degrees — what now?
- 3Use money: a balance of −20 and a deposit of 50.
- 4For subtracting a negative, use the debt story: removing a $4 debt makes you $4 better off.
- 5Play a game where moves can be positive or negative and track the running total.
If it's too hard
Ordering and simple addition on the line only.
If it's too easy
Multiplying and dividing negatives, and explaining why two negatives make a positive.
Say this
"Which one is colder? Colder is lower on the line — and lower means smaller."