Today, I’m sharing strategies for teaching 2 digit plus 1 digit addition. This skill can often include regrouping ones to create another group of ten. Before you teach this skill, I recommend students have practiced, and feel confident with, adding a 2-digit number with a multiple of 10.
Teaching Students to Trade Ten Ones for a Group of Ten
We want students to have a solid grasp of making trades to be successful with this skill. One of the most fun, and effective ways I have found to teach this skill is by playing the game roll to 100.
In this game, partners work together to roll to 100 (or a smaller number you determine) with a die and base ten blocks. When they have ten ones, they practice making a trade for a 10. This is an essential skill for students to master before learning 2 digit plus 1 digit addition.
Practicing 2 Digit Plus 1 Digit Addition
It is so important that we work on this skill at a concrete level, using base ten blocks to solve the problem. As first grade teachers, it’s important to lay a strong foundation, so students will be ready for a more abstract understanding of the skill (carrying) in the future.
I love using a write and wipe dry-erase mat when teaching this skill. Start with a 2 digit plus 1 digit addition problem that will include regrouping.
- Step 1: Students write the problem and build the 2-digit number with base ten blocks.
- Step 2: Students build the 1-digit number in the column after the addition sign. I recommend using a different color of blocks, if possible.
- Step 3: Students combine the ones, until they reach ten ones. The dots on the mat will help them!
- Step 4: Students trade the ten ones for a ten. Again, it’s great to use a different color of base ten blocks.
- Step 5: Students finish adding by combining the rest of the ones. Then, they write the sum.
Now, the process can be repeated a variety of times to build students’ fluency with this addition skill. You can grab a copy of the 2 digit plus 1 digit addition mat.
More Activities for 2 Digit Addition With Regrouping
Once students are comfortable with the skill using base ten blocks, then you can move to a representational stage. Digital activities with moveable base ten blocks are a lot of fun for students!
Worksheets and task cards are also great ways for students to continue practicing their 2-digit addition skills. Look for worksheets that include images of base ten blocks to offer students plenty of support as they make this transition to a representational stage of understanding.
These resources are available on TPT or find them in the First Grade Math Hub.
