Knock Out- A Version Of Which One Doesn’t Belong?

The activity Which One Doesn’t Belong? (WODB) made its way across the math community with a bang.

For those of you not familiar with this activity there is a display of four items. The items could be numbers, expressions, shapes or images. Students are to reason about the similarities and differences between them.

There are many versions of this routine out there. Howard County has Eliminate It! There is also an activity called One Of These Is Not Like The Others. Which One Doesn’t Belong book

Which One Doesn't Belong? math problem on a smartboard. Student were solving and teacher wrote down student responses.

As a consultant I always encourage teachers to bring this activity into their classrooms and make it a part of their routine or warm-up. In my experience, both students and teachers enjoy it. The students love the mathematical disputes, and the teachers love the conjectures the students are making.

While visiting classrooms I’ve noticed that many students are ready for a challenge or an extension of this routine. So I decided to create one.

I developed an activity called Knock Out which has students create their own WODB. The goal is for students to generate an item that doesn’t fit in with the rest. The example in the picture below (on the left) shows a student filling in something he feels doesn’t belong with the rest and should be Knocked Out.

To extend this activity even further I’ve made some templates that are completely empty. Students can then make their own from scratch.

Just like WODB, Knock Out could be used with any math concept you teach throughout the year.

The focus of these routines is discourse. What are students noticing and how are they supporting their answers? I believe written discourse is just as important. So I have included a section where students can write about their reasoning.

Students completing the Knock Out activity by filling in one part and writing an explanation below

How Do I Start?

Start off by trying a WODB routine in your classrooms. Then extend the student discussions by trying Knock Out.

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Math Struggles Ain’t Just About Numbers

Let’s be B.F.F.R—math can stress kids out. You’ve seen it: the frozen-in-place stare, the pencil tapping like it’s sending an SOS, or the classic “I CAN’T DO THIS!” meltdown before even trying. But here’s the thing—most of the time, their struggle isn’t about numbers. It’s about mindset.

What if we borrowed some life coaching techniques to help our students not just survive math but actually thrive in it? Let’s break it down into simple, practical ways you can empower your students without turning into a full-blown therapist.

 Reframe the Narrative (A.K.A. Flip the Script on “I’m Bad at Math”)

Ever notice how kids say “I’m bad at math” like it’s their official personality trait? That belief is holding them back more than any tricky word problem ever could.

How to Do It:

  • When a student says, “I suck at math,” respond with: “You’re still learning. Let’s find a way that makes sense to you.”
  • Introduce the Power of Yet: “You don’t get it… yet. But your brain is working on it!”
  • Share stories of people who struggled with math and overcame it (bonus points if you can find famous athletes, musicians, or influencers).

Remind them that they once thought tying their shoes was impossible, and look at them now—shoe-tying pros. Math is just another skill that takes practice.

Teach Emotional Regulation (Because Frustration Is a Math Blocker)

We can’t expect students to push through challenges if they’re spiraling into math-induced panic mode. When frustration kicks in, their brains hit the “I’m out!” button.

How to Do It:

  • Pause & Breathe: Before jumping to the “I CAN’T,” have students take a deep breath. Try “breathe in for 4, hold for 4, out for 4.” Simple, but it works.
  • Break It Down: Instead of tackling the whole problem at once, ask, “What’s one thing we DO know?” Small wins build confidence.
  • Normalize Struggle: Post a sign in your classroom: “Mistakes Mean You’re Learning.” Say it. Live it. Believe it! As Naruto says.

Set Micro-Goals (Because Big Goals Can Feel Overwhelming)

If a kid already feels lost, telling them “just keep practicing” is like saying, “just climb this mountain real quick.” Instead, break it into steps.

How to Do It:

  • Instead of “Get better at multiplication,” set a goal like: “Practice a doubling/halving strategy.”
  • Use progress charts so students can SEE their growth. 
  • Celebrate the small wins! Even if they only got one more right than last time—that’s growth!

Remind them “If you can memorize every single lyric to that TikTok song, you can 100% remember a few math strategies.” 
Honestly research shows long term memory is activated when we leverage different modalities in our lessons. It’s how the brain learns math.

Shift from Performance to Progress (Because Speed Ain’t Everything)

Fluency is about thinking efficiently, not racing to the answer. The goal isn’t to turn kids into human calculators—it’s to help them use numbers flexibly.

How to Do It:

  • Replace timed tests with strategy-based challenges (ex: “How many ways can you solve 12 × 8?”).
  • Instead of praising fast answers, celebrate smart strategies: “Ooooh, I love how you broke that down!”
  • Remind them that even adults use tools like calculators and sticky notes—real math is about knowing how to approach problems, not just getting the answer instantly.

 Teach Self-Talk (Because Their Inner Voice Matters More Than You Know)

The way kids talk to themselves about math shapes their experience with it. If they constantly say, “I can’t do this,” their brain believes it. Time to switch up the self-talk game.

How to Do It:

  • Teach “I can” statements: Instead of “I don’t get it,” try “I don’t get it YET, but I can figure this out.”
  • Have students write down one math strength (even if it’s “I’m good at counting on my fingers” – that’s a start!).
  • Encourage students to talk to themselves like they’d talk to a friend. Would they tell a friend, “You’re dumb at math”? No? Then don’t say it to yourself either!

Emphasize- “You wouldn’t let your best friend talk trash about you, so don’t let your brain do it either!”

Coaching Math Mindsets for the Win

At the end of the day, teaching math fluency isn’t just about numbers—it’s about helping kids believe they can figure things out. When we shift from just teaching math to coaching their mindset, we create students who are not only fluent in math but confident in life.

So, here’s your challenge: What’s one small move you can try this week? Whether it’s shifting self-talk, celebrating small wins, or breaking down frustration, pick one and run with it.

Oh, and if you want more strategies like these, check out my Figuring Out Fluency series, (Book 1) (Book 2) where we make fluency engaging, empowering, and (most importantly) actually make sense.

And if you want more math mindset strategies, grab my Guide For Teachers To Help Students With Growth Mindset