Math · Stage 5
Add and subtract with negative numbers
Picture a number line that keeps going LEFT past zero. Moving right ADDS, moving left SUBTRACTS — and subtracting a negative turns around and ADDS.
✦ Math📘 Stage 5 · S5⏱ ~12 min🧒 Ages 9–10★ Free to start
I can add and subtract with negative numbers.
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Kavi Crosses Zero ❄️
Brrr! At dawn Kavi's thermometer shows 3°C, then a cold snap drops it 7°. "Where do the numbers go when we run out of counting-down room?" hoots Kavi. "They cross zero and keep going — into the negative numbers! 3 − 7 = −4°C. Below zero isn't the end of the line; it's a whole new stretch to the left. ❄️"
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What your child will learn
1Zero is the middle, not the endThe number line does not stop at 0. It keeps going left into the negative numbers: −1, −2, −3 … The further left you go, the smaller the number. Moving right means add; moving left means subtract.
2Rewrite the signs, then countA plus next to a minus collapses to one move. + (−) becomes − (hop left). − (−) becomes + (hop right). Rewrite first, then just count along the line. Tap a row.
3Add a negative vs. subtract a negativeThese two look alike but move in OPPOSITE directions. Tap each card and watch which way you travel on the line.
4Will the answer land above or below zero?
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A peek inside
The temperature is 4°C at noon. By midnight it has dropped 9°. What does the thermometer read?
4 − 9: count back 4 to reach 0, then 5 more below zero → −5
Try this at home: Count back across zero: 2 − 5 = __
Ready to play and learn?
Start the free interactive lesson, or print the handout for screen-free play.
Part of Math · Stage 5 · S5 on KAVI Academy — a secular, whole-child learning platform for ages 5–12.