Two Digit Addition Strategies

In second grade, students are expected to solve two digit addition and subtraction problems. This week, we have been focusing on adding up to four two-digit numbers using place value and properties of addition.  So what exactly does that mean?

• Place value strategies: Splitting a number into tens and ones (decomposing) and adding the tens together, the ones together, and then adding your two sums to get your total.  In later grades, this is called partial sums.  Many of you have seen this strategy on our Educreations.

• Properties of addition: We use the commutative and associative properties of addition (though not by name,) to decide what order to add two or more numbers.  We worked on many addition shortcuts at the beginning of the year, so when adding the numbers  

6 + 4 + 6

students might decide to add 6 + 4 first, because those are making ten pairs, OR add 6 + 6 first, because those are doubles students should have memorized.  This freedom allows students to answer problems more quickly by avoiding math facts that are more difficult.

Take a look at our recent Educreations to see how we are doing solving four two-digit addition problems.  One of the biggest obstacles students face is not solving a multi-step addition problem, but getting their basic math facts right!