I show all the fact families with the sum of 9, organized into a table. Seeing the structure and the patterns in this manner helps develop number sense and helps children in the memorization work, also.
Then we drill the facts for a bit. The lesson also includes a missing numbers exercise, an exercise where we compare simple addition and subtraction expressions, and two word problems.
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Addition & Subtraction Fact Families — free online practice here at MathMammoth.com
Addition and subtraction facts with 8 — video lesson
Math Mammoth Grade 1 curriculum