Teaching addition and subtraction strategies doesn’t have to be complicated once you understand them. I wrote recently about understanding the addition and subtraction strategies, and today I wanted to share with you just how I teach them in my classroom using the math workshop model.
Teaching Addition and Subtraction Strategies
I’m going to discuss how I do it using the split strategy lessons, both adding and subtracting, from my Addition and Subtraction Strategies Math Workshop Unit. What is described below are summaries from several lessons to help you understand how I teach it to help you teach your students the strategies.
I always teach my math using the workshop model. So, I first begin with a mini-lesson where I gather my students around an easel with their notebooks in hand so they can take notes. I always create an anchor chart, with my students, about what I am talking about throughout the mini-lesson. Sometimes I write down new vocabulary on my anchor chart, while other times I just pull out my new word that I already have on a card. Either way, we discuss the vocabulary and review any previous related words. These words go up on our math word wall. Then, I teach the teaching point of my mini-lesson. Since I only have a small amount of time (usually 10-15 minutes), I have to be explicit. I model by working through sample problems while thinking aloud as I work. I repeat this process with a few extra problems. Students watch during this time. I don’t like them copying or writing because they could miss some very important processes of my thinking. (On some days we have a math warm-up, or a stretcher, prior to math workshop beginning.)
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After I work through the mini-lesson, I guide students into the active engagement. This is where the students try a few problems that I provide them with, just like what I had modeled. Often I will have students try this out with a partner while I peek over their shoulders and take note who is still struggling a bit. I write this down on a sticky pad that I carry around in my hand. Observation is an amazing assessment! After a few minutes is up, I have students share with me their answers, or sometimes I will have a volunteer come up to the easel and share how they arrived at the answer (not just tell the class what the answer is).
Then, we move into guided math. This is where students work on the lesson while I work in small groups or confer. I usually have my students work in groups or with partners to complete some sort of activity or game. Once they finish the activity or game, I have them work on an independent practice sheet (so I can determine if they are grasping it okay or need more help!).
Finally, at the end of math workshop, we gather back together for a quick closing that is related to the lesson. All of the workshop lessons are in the I do, we do, you do format.
An Addition Example – the Split Strategy
During the mini-lessons, I begin teaching the split strategy of addition by first making it concrete by using base ten blocks. Since this lesson requires me to demonstrate using blocks, I had my students stay where they were and used the doc cam. I started with two-digit numbers to make it a bit easier. I model the problem 86 + 43 for students. I pull out base ten blocks creating 86 with 8 tens and 6 ones. Then, I pull out 4 tens and 3 ones. This is a great way for me to quickly review place value with students as I model each addend. Then, I demonstrate that I’m going to add all the ones, so 6 ones plus 3 ones gives me 9 ones. Then, I do it again using the tens place. I add the 8 tens and the 4 tens to get 12 tens. Again, it’s the perfect opportunity for me to review that 12 tens is also 1 hundred and 2 tens. I model again, thinking aloud as I move my blocks around. Eventually over the days, I move into three-digit numbers and semi-concrete lessons by drawing the blocks out rather than using actual blocks. I also move away from blocks altogether and just use numbers in expanded form. (You can read about this model of gradual release in math with my Teaching Math So Students Get It post.)
During active engagement I provide each student with a quick mini-foldable and have them try it out on their own using blocks with a partner. Together we check it. We continue working on this over the several days that we are studying this addition strategy.
After it appears that students have it down, we move into guided math, where students practice the strategy. Over the few days that we focus on this strategy, they create a poster (below), where they demonstrate the split strategy, and play a game together. Clearly, they are going bananas for the split strategy!
During the independent time they complete this worksheet here below. (Which is for you to download for FREE below.)
A Subtraction Example – the Split Strategy
I teach the addition and subtraction strategies the same way. I start my mini-lesson with base ten blocks to demonstrate splitting the minuend and subtrahend. However, in the subtraction strategy, I have students use sticky notes also to mark the numbers throughout the process. I feel this helps students keep track of the numbers and see how they are changing when we trade (or regroup).
**We also spend a lot of time discussing and practicing learning the difference between the minuend and subtrahend.**
For the active engagement, during the days we spend on the split strategy for subtraction, students continue practicing the strategies by first using the base ten blocks and then working into drawings and eventually the abstract.
The real practice comes during the guided math activities when students get to manipulate base ten blocks and continue to practice regrouping. Additionally, students continue to work on engaging activities and games that reinforce the concepts.
One thing that I have always done is called my base ten blocks “chicken.” (I know, you just reread.) I have always referred to the hundred block (flat) as a chicken patty, the ten block (long) as a chicken finger (or chicken tender), and the ones block (cube) as a chicken nugget (or chicken popcorn). The kids always find this fun and memorable.
With this, I created a fun activity where students roll dice and “order” their chicken lunch and then roll the dice again to see how much they “eat” (subtract from what they ordered). Then, students record it on their meal ticket (practicing the split strategy).
Again for independent practice, students complete the sheet below for me to gauge students’ understanding.
When students have grasped the split strategy, then it is time to move on to the jump strategy and the shortcut strategy. Teaching addition and subtraction strategies can be done in a way that can help students add and subtract effectively and more efficiently
The general thought here is that teaching lots of concrete activities that are first modeled then practiced will help your students grasp both addition and subtraction strategies faster and with better retention.
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And if you want to learn more about using the math workshop model in your classroom, check out my post What is Math Workshop? to get you started.