Adding and Subtracting within 20
Aligned to 1.OA.C.6 — Common Core State Standards for Mathematics.
What this lesson teaches
We can add and subtract bigger numbers by using strategies: counting on, making a ten, or using a fact we already know.
Worked example
8 + 5: make a ten first. Take 2 from the 5 to make 8 into 10, leaving 3. 10 + 3 = 13.
Practice questions
- Solve 9 + 4 by making a ten.
- Solve 15 − 7.
- If 6 + 6 = 12, what is 6 + 7?
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
Suma y resta hasta 20
Podemos sumar y restar números más grandes usando estrategias: contar hacia adelante, formar una decena o usar un dato que ya conocemos.
Ejemplo: 8 + 5: primero forma una decena. Toma 2 del 5 para convertir el 8 en 10, y te quedan 3. 10 + 3 = 13.
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