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 creating equivalent but easier or known sums
(e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).
Common Core: 1.OA.6
Mental Math Strategies: Use Known Equivalent Sums
This video explains how to use mental strategies to add within 20 using known sums to solve unknown sums. 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 within 20. Eventually students will memorize these facts, which is expected by the end of grade 2.
6 + 7 = 6 + 6 + 1 = 12 + 1 = 13
6 + 8 = 6 + 6 + 2 = 12 + 2 = 14
9 + 7 = 7 + 2 + 7 = 14 + 2 = 16
Double Plus 1 Addition Facts
“Double plus one” facts are based on knowing doubles first, then just counting on one. This allows students to answer questions in which two adjacent numbers, such as 4 and 5, are added: Double 4 = 8, so 4 + 5 = 8 + 1 = 9.
Near Doubles - Doubles Plus One
Examples of a math strategy called Doubles Plus 1 or Near Doubles to help students with math facts.
Doubles and Near Doubles
Addition Strategy (Doubles).
When adding near doubles, add the two doubles and then 1 more
When they are apart by two, here is what you need to do. Add the two doubles and then 2 more.
Math - Doubles Strategies
Doubles Plus One and Doubles Minus One
This video describes using the doubles strategies for addition doubles plus 1 and doubles minus 1.
How to add and subtract using doubles and near doubles?
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