# Which Number Doesn’t Belong? Math Challenge

I love providing my kids with **unique math challenges**. Sometimes this means logic puzzles, sometimes mental math challenges, and sometimes it means applying math to their current interests. I want to encourage a love for the **beauty of math**, as well as challenge them to **think deeply** about what they’re learning. I also want to help them see that mistakes are a necessary part of math learning. But I also want to show them that math is not always as straight forward, “exactly one right answer” as many would believe. Which is why I’m so excited to share this **critical thinking math challenge for kids**: **Which Number Doesn’t Belong?**

I love this post from Christopher at Talking Math with Your Kids. He is writing a completely new and different type of “shapes” book for kids (available soon). His post inspired me to come up with a version **using numbers**.

I’m sure this is not a new concept, but I had fun creating this and trying it out with my husband and kids.

The beauty of this critical thinking math challenge, is that there are **so many possible right answers**!

So I hope it encourages you and your kids to come back to them again and again to try and come up with a new solution and supporting reason.

And I hope it challenges any preconceived notions you or your students have about there always being exactly one right answer. ðŸ˜‰

**How to Use Which Number Doesn’t Belong?:**

The concept is simple enough.

Each page has **a set of four numbers**.

The object is to determine **which number doesn’t belong in the set** and provide a **true and valid reason** for your answer.

What I love is that these are great for kids **as young as kindergarten** and **as old as high school**.

I created each set with **at least 2 or 3 possible answers** in mind, but when writing out the “possible solutions” page, I **found even more** as I contemplated the sets more deeply.

My challenge to you: **find a solution for one of the sets that I didn’t include**! ðŸ™‚

**Included in the Which Number Doesn’t Belong? Set:**

This download includes **ten math challenge sets**.

First, are **ten full size pages** that you can use for a large or small group activity. If you are a classroom teacher, you might turn these into projector slides or use a doc camera and post them at the front of the class.

You could use this as a **fun math warm up** as kids begin class. It’s also a great way to **spark a math conversation** (or debate ðŸ˜‰ ).

This download also includes **ten half sheets** which you can use as **individual assignments**. These include a space for kids to **write out their solution and reasoning**. Then there’s a second question which challenges kids to find *another solution* and explain their reasoning.

You could use this as an **exit ticket** or **quiet activity** for kids who have **finished their assignments**.

**Please note**: though there are two different versions (so you can use it different ways), there are **only ten sets**. The full page and half page versions are the same, just different formats.

Also included in this download is **a “possible solutions” page** for teachers and parents. I debated including this, because I wanted to leave it open-ended and encourage math talks.

But I also want to **provide support for parents and teachers**, so I hope this gives you a good starting point as you discuss with your kids.

Want to download this set for your home or classroom? Click the link below to get it FREE in my shop!

**{Click HERE to go to my shop and get a copy of the “Which Number Doesn’t Belong?” math challenge for kids!}**

**Want more unique challenges for your kids? Try one of these!**

- Mental Math Challenges
- System of equations puzzles
- Hands on logic puzzles (with pattern blocks)

And be sure to check out this post: How to Raise Logical Thinkers and Why it Matters

Brings out great classroom duscussion