In 2nd grade, we teach three digit addition strategies. Students love these lessons because they are excited to work with bigger numbers. They grow their confidence in math when they can solve three digit addition equations accurately.

 

 

Luckily students have already learned two digit addition strategies. These are similar to the three digit ones, so students catch onto these quickly.

 

But some students can still really struggle. So how do we really help students master three digit by three digit addition?

 

So I thought it would be helpful if I shared 3 elements that I incorporate into my three digit addition lessons that help students master these strategies.

 

If you want to know exactly how I teach each three digit addition strategy, check out these blog posts below:

Open Number Line

Partial Sums

Mental Math

Three Digit Addition Regrouping – Standard Algorithm

 

It’s also important to note that students do best with these strategies when they have a solid foundation of place value concepts with three digit numbers. They need to know exactly what each digit in a three digit number means. Learn more about how to teach these place value concepts in this blog post here.

 

Okay, let’s get into the 3 elements I add into my three digit addition lessons:

 

Three Digit Addition

 

Scaffolded Lessons

 

What I mean by scaffolded lessons is that I set my lessons up in a way to guide students and give them the support they need.

 

I start by giving students a lot of support and then I slowly take away that support. By the end of the lesson, students can use the strategy to solve three digit addition equations.

 

The first bit of scaffolding I provide is teaching the mental math patterns involved in the strategy. For example, with the open number line strategy, students need to know how to add 100, 10, and 1 to a three digit number.

 

To help students learn these mental math patterns, I use display pages. These have equations that match the mental math skills. I post these up and we solve the equations together as a class. We use base ten blocks to find the answers quickly and in a visual way. Then I simply ask students what patterns they see.

 

 

Students can see that when you add 100, the number in the hundreds place increases by one. They can see when adding 10, the number in the tens place increases by one. And they see that when they add 1, the number in the ones place is increasing by one.

 

When students know these mental math patterns, it helps them solve three digit addition problems.

 

After students know these, I give more support by modeling the strategy. Then I have students help me solve problems. They help walk me through what I should do next.

 

Then it is time to give students their own practice. I have them do a three digit addition worksheet. I display this worksheet up on the board as well, then we do the first couple of problems together.

 

Then I let students do the rest by themselves. But I still provide support by walking around, monitoring students, and giving individual help when needed. After students finish those, I call students’ attention back and I review any common mistakes I saw.

 

Then I give students another worksheet as independent practice. This time students complete it on their own. I wait over at our classroom table. When students finish, they line up by me. I quickly check their work and help them fix any mistakes. I love how this gives students immediate feedback. To show students have completed the assignment, I mark their page with a big check mark using a smelly marker. This is also like a reward for students. They want to know what the day’s smell is.

 

Then students then put this page in their Take Home Folder. Parents can see how their child did on the assignment.

 

Three Digit Addition Worksheet

 

Not only does the set up of my lesson provide scaffolding, but the three digit addition worksheets I have students do are scaffolded as well.

 

Let me give you an example with my partial sums worksheets.

 

First students complete a worksheet where the numbers are lined up for them in a hundreds, tens, and ones chart. The next worksheet has the numbers lined up not in a chart. Students have to line their partial sums up correctly underneath the starting numbers, but the worksheet does label each line to support them. Then students are one their own! They line up the numbers without any labels or charts to solve three digit addition word problems.

 

 

Do you see how these worksheets gradually take away support until students can use the strategy by themselves? This really helps students as they learn three digit addition. Find all the scaffolded worksheets I use here.

 

Review Strategies

 

Here’s the thing. If your curriculum teaches a new three digit addition strategy every day of the unit, students are going to forget how to do that. That’s why I review the strategies.

 

I do this in a simple way that doesn’t take up a lot of class time. As our math warm-up for the day, we review the previously learned strategies. I write an equation up on the board. Then I tell students which strategy we are using to solve the problem. Students raise their hand and tell me the steps I need to solve. I follow along and write everything they tell me to do until we have solved the problem.

 

So let’s look at an example. Let’s say the first day of the unit I teach the open number line strategy. The next day I teach partial sums, but before I say anything about partial sums, I review the open number line strategy by solving an equation with the class. The next day I teach the mental math strategy. But first, we solve a problem using open number line and another problem using partial sums. The next day I teach three digit addition regrouping. But first I review open number line, partial sums, and mental math. Do you see how each day builds on that review?

 

After I have taught all the strategies, as our review math warm-up, I will make an anchor chart featuring all the strategies. I get an outline ready with the headings and the equations. Then students tell me how to solve as I record the numbers on the chart.

 

 

Then I display this three digit addition anchor chart on our front white board for everyone to see. We have a math lesson where students can choose any strategy they want to solve. The anchor chart helps students choose a strategy that will work for them and reminds them how each strategy works.

 

To also review the strategies, I like to include fun three digit addition activities for math centers.

 

Make It Fun

 

For fun center activities I like to have my students do scoot activities and puzzle activities that get them even more practice with three digit addition.

 

For the scoot activity, I tape up task cards around our classroom. Students have a recording sheet and they go around to the different task cards and solve the problems using a certain strategy. I set out an answer key for students to check their work with a red pen.

 

 

Students love these scoot activities because they get them up out of their seats and moving. They enjoy going around to different problems and solving them. Find the scoot activities I use here.

 

My students also love puzzle activities. These have different pieces to show how three digit by three digit addition equations are solved with a strategy. Students have to find the matching pieces and put them together.

 

 

These are really engaging for students because they are out of the norm. Normally students are using a pencil to solve these equations, but for these activities they don’t need a pencil. They are working together with their center group to find the pieces, and as a result they are also practicing the three digit addition strategies.

 

Find the puzzle activities I use here.

Another fun activity to have students do is a three digit addition regrouping treasure hunt. I make little booklets for students. These booklets tell students to find certain kinds of equations. For example, one may ask students to find an equation with only odd numbers. I have the different equations taped up around the classroom. Students search around the classroom, record the equation, and then solve it using regrouping. My students find this so engaging. They are searching so hard and also working hard to solve problems. Plus, it has a pirate theme and they think the little booklets are cute.

 

 

Grace M. is a second grade teacher who did this treasure hunt activity in her classroom. You’ve got to hear what she said about it, “My students absolutely LOVED the treasure hunt activity! It was an engaging way for them to practice adding three-digit numbers as well as place value.”

 

Find this treasure hunt activity to use in your classroom here.

 

Okay, so let’s do a little recap of the things to include in your three digit addition lessons. First teach each strategy in a scaffolded way. Next, review the strategies often. And finally, help students get the practice they need with fun activities.

 

I hope you have found this blog post helpful. Find all of my three digit addition materials in a money-saving bundle here.

 

Teaching three digit subtraction soon? Find those resources here.

 

Learn more about teaching three digit subtraction strategies in this blog post here.

 

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