Adding and Subtracting within 20
Aligned to 2.OA.B.2 — Common Core State Standards for Mathematics.
What this lesson teaches
Use quick tricks to add and subtract small numbers in your head. Making a 10 helps a lot.
Worked example
8 + 5: first make 10 by taking 2 from the 5 (8 + 2 = 10), then add the leftover 3: 10 + 3 = 13.
Practice questions
- Add 9 + 6.
- Subtract 15 - 7.
- Add 7 + 8 by making a 10 first.
Watch the lesson
Every lesson comes with a video taught in English and Spanish — the same video the QR code in the printed workbook opens.
▶ Watch this lessonEn español
Sumar y restar hasta 20
Usa trucos rápidos para sumar y restar números pequeños de memoria. Formar un 10 ayuda mucho.
Ejemplo: 8 + 5: primero forma 10 quitando 2 al 5 (8 + 2 = 10), luego suma el 3 que sobra: 10 + 3 = 13.
More Operations & Algebraic Thinking lessons
Arrays — Foundations of Multiplication2.OA.C.4Word Problems with Addition and Subtraction2.OA.A.1Odd and Even Numbers2.OA.C.3
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