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When you’re teaching 2-digit addition, it’s not enough to stick with just one method.
Students benefit from seeing multiple strategies – but if you’re looking for one that really clicks and helps them visualize their thinking, the addition open number line strategy is a must-have in your toolkit.
This method makes it easy for students to break apart numbers, make tens and ones jumps, and actually see the math happening in real time.
It’s also a great bridge between concrete and abstract thinking.
But before you jump right into using an open number line, make sure your students have a solid foundation.
Build Up to the Open Number Line with Intentional Strategy Progression
I always recommend starting with base ten blocks to help students get a concrete understanding of place value.
Then, move on to the break apart strategy, which teaches students how to decompose numbers into tens and ones – something they’ll rely on heavily once they start using an addition open number line.
Each strategy builds on the last.
And once your students are ready, the open number line becomes the perfect way to help them visualize the math and gain confidence with 2-digit addition.
The standard 2.NBT.5 allows for flexibility in how students learn to add and subtract two-digit numbers, and using an addition open number line gives them another powerful option.
Build Up to the Open Number Line with Intentional Strategy Progression
The addition on an open number line isn’t just a fancy trick.
It actually helps students organize their thinking and build number sense.
Here’s how it works:
Let’s say you’re solving:
Start with a blank number line.
I like to begin with the larger number – so I’d place 34 on the far left. That’s our starting point.
First, jump 10:
34 -> 44
Jump another 10:
44 -> 54
Now add the ones:
54 -> 55 -> 56
Now we’ve made two jumps of 10 and two jumps of 1. The answer is 56.
Students are constantly making decisions about how to break apart numbers, and the visual layout of the number line helps them see their steps clearly.
It’s also much easier to check their work and correct mistakes when they have each step written out.
Want your students to remember to write the sum after each jump?
I tell them it’s like an airplane taking off from one airport and landing at another – don’t take off again until you know where you’ve landed!
Different Ways to Use the Open Number Line
What makes the addition open number line strategy even more powerful is how flexible it is.
Some students might take two jumps of 10, while others might jump 20 all at once.
Some might start with the other addend and still arrive at the correct answer.
Others might be ready to make one big jump of 22.
This flexibility allows you to meet your students where they are – without needing to change the overall method.
That’s a win for differentiation.
Give Your Students the Practice They Need
If you want your students to really understand 2-digit addition without regrouping, you need more than just a one-time demonstration.
You need structured, targeted practice that builds confidence and consistency with the addition open number line.
I’ve created a set of low-prep practice worksheets that are perfect for introducing, reviewing, and reinforcing this strategy.
Whether you’re teaching whole group, working with a small group, or assigning independent work, these pages give your students the support they need.
👉 Click here to grab the full Addition Open Number Line Practice Pack on TPT
Want to try this strategy with your students before committing to the full resource?
Download the free sample worksheets and see how it works in your classroom.
Need help or have questions?
If you need help or have questions, the easiest way to reach me is to DM me on Instagram @techieturtleteacher.
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