Videos and songs to help Kindergarten and Grade 1 kids learn to add and subtract within 20, demonstrating fluency for addition and subtraction within 10 by using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 – 8 = 4).

Common Core: 1.OA.6

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More Lessons for Grade 1

Common Core for Grade 1

Mental Math Strategies: Addition & Subtraction Relationship

This video explains how to use mental strategies to add and subtract within 20 using the relationship between addition and subtraction. This is one of the strategies suggested in the Common Core State Standards for Mathematics, 1.OA.6 and 2.OA.2.

With practice, this strategy can help students gain fluency when adding and subtracting within 20. Eventually students will memorize these facts, which is expected by the end of grade 2.

12 - 8 = is the same as 8 + _ = 12

13 - 6 = is the same as 6 + _ = 13

15 - 7 = is the same as 7 + _ = 15

Thinking Addition is a mental math strategy that introduces students to the concept that there is an inverse relationship between addition and subtraction. This video outlines the basic ideas behind thinking addition, as well as introduces a couple of techniques for teaching.

Max has 15 marbles. He let Rosa have 6 of his marbles. How many marbles does Max have left?

The Common Core State Standards (CCSS) videos are designed to support states, schools, and teachers in the implementation of the CCSS. Each video is an audiovisual resource that focuses on one or more specific standards and usually includes examples/illustrations geared to enhancing understanding. The intent of each content-focused video is to clarify the meaning of the individual standard rather than to be a guide on how to teach each standard although the examples can be adapted for instructional use.

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