Today is rung 9 of 13 on this topic
All four operations with negatives, fractions and decimals
Can do: Adds, subtracts, multiplies and divides any rational number confidently, including mixed forms.
Why it matters
From Grade 7 on, negatives appear inside every other topic. Slow or unreliable arithmetic here costs marks everywhere else.
What it looks like when it's wobbly
Sign errors, especially subtracting a negative and multiplying two negatives, and freezing when a fraction is negative.
โฑ๏ธ Two-minute check
"โ3 โ (โ7)? โ2/3 ร 3/4? โ0.5 รท 0.25?"
Solid looks like: 4, โ1/2, โ2.
The full activity for this topic ยท 20 minutes
Sign Rules from the Pattern
- 1Build the multiplication pattern down: 3ร2, 2ร2, 1ร2, 0ร2, โ1ร2. The pattern continues into negatives on its own.
- 2Do the same for a negative multiplier so the two-negatives rule emerges rather than being announced.
- 3For subtraction, rewrite every subtraction as adding the opposite, always.
- 4Do a mixed set of ten and check each sign before calculating the value.
- 5Estimate the sign of the answer first โ that catches most errors.
If it's too hard
Integers only, on a number line.
If it's too easy
Multi-step expressions mixing negatives, fractions and decimals with brackets.
Say this
"Before you work out the number โ is the answer positive or negative? Decide that first."