How to Prevent Teen Number Reversals With One Easy Activity

I cringe when it happens- a student brings you a piece of work they are so proud of. They have figured out a tricky story problem or have used blocks to add two numbers together. Their thinking is exactly correct. But their answer? It's written in reverse. Thirteen has turned to 31.

You want to praise the student for their work and their thinking, but that pesky teen number is sticking out like a sore thumb and you are stuck wrestling with whether or not you should say something *right now* even though it may crush their little spirit.
Don't crush her spirit... help her understand! 

I'm not being dramatic. I know you wrestle with the same. exact. problem. Your students can count teen numbers but what you need to do is to help them understand teen numbers. 

If this sounds like you, I have an easy-as-can-be teen number activity you need to try immediately! Grab a double ten frame, some fun counters, and a whiteboard and you are on your way to solving this problem once and for all!

THIS Activity Will Solve Your Problem!
Teen Number Ten Frame Activity

  1. Start by giving each student a double ten frame and ask each of your students to build a teen number such as 14 on the ten frame using counters. 
  2. Ask your students how many counters they see on the top ten frame (10) and how many they see on the bottom ten frame (4). 
  3. On the whiteboard, record what your students have built as a number bond. Do a think-aloud as you are writing telling your students "We had 10 in the top and 4 on the bottom and together that made the number 14". 
  4. Next, ask each of your students to record the same number bond on their own whiteboard. 
  5. Ask your students to state an addition equation that matches the number bond you completed together. As you are writing the total, tell your students "I had 1 ten and 4 more ones" as you write. 

And That's All I Need To Do? 

The real secret to this activity is repetition. For some of your students, one time through this activity is enough. They will see the ten, they will see "some more ones" and they are good to go! 

For other students, it will take many days. Many days before they truly notice each teen number has a group of ten and some more ones. 

One More Tip

While the activity itself is important, the way students to transition from one problem to another is so important for you to notice! Consider these different approaches to building the number 18 after number 14 and what they tell you about the students.
  1. Student #1 clears the entire board and builds 18 by counting out individual counters starting at one. 
  2. Student #2 keeps the top ten frame but clears the bottom and counts out 8 counters. 
  3. Student #3 doesn't clear their board at all and adds 4 counters to make the number 18. 
  4. Student #4 clears the bottom ten frame but doesn't appear to count as they place 8 new counters in the bottom ten frame- they "know" what 8 looks like in a ten frame. 

I Love This... But What Will I Do Next? 

This is a very concrete activity using individual counters. Your students still have room to grow! Moving forward try activities that: 
  • Use a pre-grouped model of tens and ones. 
  • Use a different representation than a double ten frame. 
  • Move from concrete materials to a representative model 
  • Move towards fluency with 10 + facts resulting in a teen number total. 

AND, the next time your student comes to you beaming, ready to show you their math work, you won't have to wrestle with yourself- you'll be jumping for joy because they understand! 

Related Resources

Teen Number TPT Unit
This 5-Day Unit has EVERYTHING you need to lead a successful unit on understanding teen numbers to a small group of students. Assessment. Daily Lessons. Independent Activities. Tickets Out The Door. EVERYTHING

Research-Based Strategies 

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How To Plan Effective Math Intervention: A Powerful Free Guide

It's a funny thing pre-planning for intervention groups. Every summer I would find myself wanting to map out the topics I knew would be most important for my students in the coming year. At the same time, I had odd feelings of guilt or that I was doing something irresponsible. Should I be waiting to meet my new groups instead of trying to fit them into a mold that works for me?

This tug of war that interventionists feel is completely normal. Over the years, I came up with a solution that works for me. It honors the fact that my students have individual needs (that's why they are coming to see me in the first place!) but it also acknowledges that I have real and specific goals I would like my students to meet by the end of the year and it gives me a road map to make that happen.

My planning strategy starts out looking like a lot of other teachers planning.

But then I take a turn.

It's unexpected but incredibly effective!

How Can I Get Started? 

First things first, look at your grade level curriculum and notice the foundational skills that your students will need to be successful with grade level work. List these topics out first and order them chronologically.

Next, look at the units you will be teaching during the school year and list out the most important skills and strategies that you can't let your students leave the year without. I personally like to group these topics broadly so I can see the overarching scope of my year. 

This example lists the 1st-grade math intervention topics I use in my intervention lessons

I Already Do This... Where Is The Twist? 

In my example above you see that I have only listed out 14 topics. Never will you ever come across a textbook publisher who only gives you 14 weeks of instruction for the school year. But that's exactly what I advocate doing. You are looking for the most important topics because you want to have plenty of time not only to cover those topics. But to teach for mastery. 


We can all agree that a math interventionist feels the most pride when our students never need math intervention again.

Never. Ever. 

Now that I have my list of topics, I look across the year making sure that I never get close to or ahead of the classroom pacing. By building in time for foundational skills at the beginning of the school year this is almost always the case. I block out the general time of year that I would like to hit each of these topics. 

Grab a cup of coffee, turn on some music and let yourself just play with your list and the timeline of the school year. 

So Under-Planning is the Secret? 

Under plan and over deliver. See, when you break down your planning to only the most critical components you will be able to plan in the thing that your students need most.


When I plan, I give myself a week for initial implementation for a unit. Often I will plan in another week for follow-up. I never feel the rush during the first week of implementation. If my students need another day on a topic- fine! I build in a nice wide buffer.

If most of my students are flying through the unit that's great! They will get more time to work on math centers (more on that below!) and I will have the time to work 1:1 or 2:1 with the students who need that extra time and attention.

Now You Have My Attention

I'll bet I do :) After the second week of implementation I build in ANOTHER buffer week. This time, I want to make sure I have time to do progress monitoring on fact fluency and I want to make sure my students have time for math centers. 

I pick my centers based on all of the standards we have worked on up until this point in the year, all of the fluency activities they have learned and all of the independent practice activities within the units of study. My students have no shortage of important work to do. 

And it is important! 

One of the most effective ways to move students understandings to long term memory is for students to practice the skill of recall. And when I bring back "old" centers or skills my students are getting plenty of time to recall and solidify their skills. 

You Promised Me A Guide

I'm getting to it! Click HERE to go and download a free planning guide to help you lay out your math intervention year. 

This FREE guide will start by looking at the whole year and planning out your major units, leaving space for the buffer weeks I described above. Each month, you will take your master plan and lay out your next 30 days. Weekly, you will zoom in on the needs of your students and determine what specific teaching moves you will make to help them to be most successful! 

Research-Based Strategies 

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