Math manipulatives are an essential part of elementary education. For years my go-to manipulatives were base 10 blocks, fraction tiles, and pattern blocks. I used them with place value, subtracting whole numbers, and pretty much every fraction concept, including when I taught students to subtract mixed numbers.
They did help my students learn, but these hands-on resources caused a lot of frustration. Not only did they take a lot of time to pass out and collect, but half of them would also wind up on the floor!
Oh, and the noise…the noise!!! Can we please make all math manipulatives out of foam? I soon discovered a much better resource that would end my frustrations for good.
In 2018, I was lucky enough to attend not one, but TWO of Greg Tang’s conferences. If you ever get the chance to see him, it will change your teacher-life forever!
It was during his conference that I discovered the magic of teaching with unifix cubes. My mind was BLOWN!
Although I had these manipulatives in my classroom, my students mainly used them during indoor recess. In my mind, unifix cubes seemed more suitable for primary grades, so I never considered them when teaching 4th or 5th grade.
But my mindset changed as I watched Greg Tang teach several upper elementary skills using unifix cubes. They quickly became my manipulative of choice and were a regular tool my students used when first learning a concept.
What Sets Unifix Cubes Apart
Remember my beef with manipulatives I mentioned earlier? Well, unifix cubes are different. For starters, they are SUPER EASY to distribute and collect. In addition, they are simple for students to assemble, and because of this, they are much less likely to end up on the floor.
Since learning about unifix cubes, I’ve incorporated them when teaching prime and composite numbers, multiplicative comparisons, and converting improper fractions & mixed numbers. However, my favorite skill to pair unifix cubes with is subtracting mixed numbers with regrouping.
Subtract Mixed Numbers with Regrouping
The first time I used them with this lesson, I was SHOCKED! My students actually understood what they were learning, and they were having FUN!
We then progressed to solving problems without manipulatives. I was in even more shock as I watched my students solve these problems with ease. This strategy was WORKING!
In that moment, I wanted to give Greg Tang a gigantic hug and thank him for sharing his brilliant ideas. So, how exactly do these manipulatives work with subtracting mixed numbers? I’m so glad you asked!
Let me walk you through two examples.
Step 1: Model with Unifix Cubes
To begin, have students model the mixed number they are subtracting from with their unifix cubes. In this example, they would model 3 and 2/5.
Since the denominator is 5, each whole number represents 5/5. Therefore, three groups of 5/5 are placed on the whole number side, and 2/5 are placed on the fraction side.
This first step alone is an important concept for 4th graders!
In fact, I recommend having your students model 3-4 mixed numbers before you even begin subtracting just so they get the hang of it.
Step 2: Regroup the Mixed Number
Next, it’s time to regroup the mixed number in order to subtract the fractional parts.
Modeling with unifix cubes helps students see why they need to regroup. How can they take away 4/5 when they only have 2/5?
By moving one whole over to the fraction side, they will understand why the 3 becomes a 2, and why the 2/5 changes to 7/5. This is the most difficult step, and unifix cubes make this crystal clear.
Step 3: Subtract and Solve
Finally, students subtract the fractions and whole numbers. Make sure to use a variety of denominators to reinforce how they affect regrouping. It’s also important to practice subtracting fractions from whole numbers. Students often struggle when there isn’t a fraction to subtract from.
Example #2
Watch this video to see another example of subtracting mixed numbers from start to finish.
This is from my Subtract Mixed Numbers with Regrouping PowerPoint lesson you can find linked below.
Subtract Mixed Numbers Resources
Are you ready to get started teaching with unifix cubes? I know you are! The work mat used in the examples is FREE and can be used during your whole group lesson or in small groups.
Full page and 4-to-a-page versions are included. Both can be glued in notebooks or placed in dry erase sleeves.
Click the button to grab this freebie!
Subtract Mixed Numbers Task Cards
Task cards are my go-to math resource because of their versatility. Whether used as a daily warm-up, practice for small group centers, or posted around the room for a gallery walk, task cards are effective and easy to use.
The first set includes images of the unifix cubes to reinforce the whole group lesson. The digital version includes moveable pieces to guide students as they solve!
The second set is less guided without the models. The questions increase in difficulty and have students subtract from both mixed numbers and whole numbers.
The editable PowerPoint Lesson includes printable and digital activities to use in math centers. All of these resources will support your students as they learn how to subtract mixed numbers with regrouping!
What Teachers are Saying
Want to know what other teachers are saying about these resources? Looks like I’m not alone in my love for unifix cubes!
Brittanie: “I downloaded your free template using these unifix cubes and used it with my summer school students this year. They instantly made the connection and understood it better than they did during school. They were all saying things like “this makes so much sense now” or “this is so easy this way”.
Kelly: “This was really helpful for teaching my fourth graders about fraction subtraction with regrouping. I never thought to use linking cubes before. I had my students make the problems with the cubes and then used this product on the Smartboard. It was great! Thank you!”
Amanda: “My kids were so stuck on this until I used this resource! Next year I am going to start my unit with this! Thank you!!!”
Teaching with Unifix Cubes
If you’re ready to get started teaching with unifix cubes, be sure to listen to Episode 26 of Elementary Math Chat where I share 4 additional skills you can teach with unifix cubes. This episode will make you love unifix cubes even more!
Listen by clicking the button or through your preferred listening app.
Until next time,
Happy Teaching!
P.S. If work mats are your thing (and I hope they are), you’ll want to read this BLOG POST!