🔢 Adding and Subtracting to 20

What you’ll learn

1. Fast Facts within 5Fluently add and subtract within 5, moving from counting to just knowing.Small facts within 5, like 2 + 3 = 5 and 5 - 2 = 3, can live in your memory. You can even learn to see small dot patterns without counting. Fast small facts make every bigger problem quicker.
2. Counting On to 20Add within 20 by keeping the big number and counting on the small one.Teen numbers are a ten with extras riding along — 14 is 10 and 4. To add, keep the big number and count on: for 14 + 5, say 15, 16, 17, 18, 19. Fingers can track the hops so you never lose count.
3. Counting Back within 20Subtract within 20 by counting back, and check answers by adding.To subtract from a teen number, hop backwards: for 17 - 3, hop 16, 15, 14. Only hop the number you take away. Adding checks your work — 14 + 3 = 17 — because adding and subtracting undo each other.
4. Zero and Choosing a StrategyAdd and subtract with zero, and choose the right strategy for problems to 20.Zero is the nothing number: 8 + 0 = 8 and 8 - 0 = 8, while taking away everything leaves zero (6 - 6 = 0). With fast facts, counting on, hopping back, and zero tricks, you have a full toolbox for adding and subtracting to 20.

Questions this course answers

Grounded in trusted sources

• Khan Academy Kids
• PBS Kids — early math
• NAEYC — early math learning
• Britannica Kids

Every Wunder lesson is built from real, reputable sources — never invented.

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