⚡ Addition and Subtraction Facts to 20

What you’ll learn

1. Fact FamiliesRecall facts to 20 like 7 + 8 = 15 and use fact families to know 15 − 8 = 7 instantly.Three numbers like 7, 8, and 15 form a fact family with four facts: two additions and two subtractions. Knowing 7 + 8 = 15 means you also know 8 + 7 = 15, 15 − 8 = 7, and 15 − 7 = 8. Families turn subtraction into facts you already own.
2. Doubles PowerKnow doubles to 20 by heart and use them to solve near-doubles like 7 + 8 = 7 + 7 + 1 = 15.Doubles like 6 + 6 = 12 and 7 + 7 = 14 are easy to remember and show up all around you. They unlock near-doubles too: 7 + 8 is just double 7 plus one more, so it's 15. Double it, add one — new facts from old!
3. Grow Your FactsUse small facts to derive tens facts up to 100, like 6 + 4 = 10 so 60 + 40 = 100.Every little fact grows into a big one when ones become tens. 6 + 4 = 10 means 6 tens + 4 tens = 10 tens, so 60 + 40 = 100. It works for subtraction too: 9 − 4 = 5 grows into 90 − 40 = 50. Your small facts do big jobs!

Questions this course answers

Grounded in trusted sources

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

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

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