Getting to a Decade Number

Videos for Educators

Important Information:

Students need to understand the value of using 10 as a benchmark number when adding within 20 so that they can transfer that skill when adding within 100, and again transfer it to adding within 1000. Using tens to solve math facts helps students develop a strategy for solving facts and it leads toward students being able to solve two- and three-digit addition problems.

Examples of what students might do:

Examples of what students might say:

" I added 4 to get to 50 and then took jumps of ten. I then had to add 4 more at the end."

"I took away 3 to get to 70 and then took away jumps of 10. I then had to take away 3 more to get my answer."

Strategies to Support Student Learning:

• Use an open number line to help students visualize the strategy

• Practice splitting numbers into their place value and helping students see what smaller numbers make up larger numbers.

• Using place value mats and base 10 blocks when composing and decomposing numbers.