For teachers

Slices in the classroom

Twenty short lessons, each aimed at one fraction misunderstanding you’ve probably seen this week. Students start from a link, with no logins and nothing to install.

Browse all 20 slices Open the Fraction Lab

Ways teachers use Slices

Warm-up predictions

Put a slice’s first question on the board and take a vote before anyone explains. The reveal that follows starts a good argument.

Link to the exact misunderstanding

Every slice has its own address. Send the one that matches the mistake you spotted in today’s work.

A starting-point check

Find my first slice asks up to eight questions and suggests where each student might begin.

Exit tickets

Every slice ends with practice questions. The answers are on the page for you, tucked away so students try first.

Talk moves

Each slice suggests what to avoid saying and what to try instead, so your explanations build on the model.

The Lab on the projector

With a free teacher account, build any two fractions in the Fraction Lab and cut them into same-size pieces while the class watches.

What a slice does, and why

Every slice runs the same way. Students commit to a prediction before any explanation. Then they see what their answer means in a picture, with no red cross, and change the model themselves until the relationship shows. Two new questions follow, with different numbers and a different representation, and the idea comes back on a later visit.

We don’t call an idea understood for now until a student has answered correctly twice, with different examples. One lucky guess doesn’t count, and one slip later on only reopens the idea.

The starting-point check works the same way. Each answer is a clue, not a verdict: we only suggest a misunderstanding with confidence once a second question points the same way.

Common Core alignment

We don’t assume any particular curriculum. For US classrooms, here’s how each slice lines up with the Common Core State Standards for Mathematics.

Slice	Family	Standards
01 · Equal Means Equal	Parts & Wholes	3.G.A.2 2.G.A.3 3.NF.A.1
02 · What’s the Whole?	Parts & Wholes	3.NF.A.3.d 3.NF.A.1 4.NF.A.2
03 · The Bottom Number	Parts & Wholes	3.NF.A.1 3.NF.A.2.a
04 · The Top Number	Parts & Wholes	3.NF.A.1 4.NF.B.3 3.NF.A.2.b
05 · Fractions of Collections	Parts & Wholes	3.NF.A.1 5.NF.B.4.a
06 · The Bigger Denominator Trap	Fractions Have Size	3.NF.A.3.d
07 · The Bigger Numerator Trap	Fractions Have Size	4.NF.A.2
08 · More Than One Whole	Fractions Have Size	3.NF.A.3.c 4.NF.B.3 3.NF.A.2.b
09 · Counting Spaces, Not Ticks	Fractions Have Size	3.NF.A.2.a 3.NF.A.2.b
10 · One Number, Not Two	Fractions Have Size	3.NF.A.2 3.NF.A.2.b
11 · Different Numbers, Same Amount	Same Value, Different Forms	3.NF.A.3.a 3.NF.A.3.b 4.NF.A.1
12 · Simplifying Doesn’t Shrink	Same Value, Different Forms	4.NF.A.1 3.NF.A.3.b
13 · Same Bottom, Compare the Top	Same Value, Different Forms	3.NF.A.3.d
14 · Same Top, Compare the Pieces	Same Value, Different Forms	3.NF.A.3.d
15 · Compare Without Guessing	Same Value, Different Forms	4.NF.A.2
16 · Adding Different Pieces	Working With Fractions	5.NF.A.1 5.NF.A.2
17 · Keep the Unit When Adding	Working With Fractions	4.NF.B.3 4.NF.B.3.a 4.NF.B.3.d
18 · Taking Pieces Away	Working With Fractions	5.NF.A.1 5.NF.A.2 4.NF.B.3.a
19 · Multiplication Can Make Smaller	Working With Fractions	5.NF.B.4.a 5.NF.B.4.b 5.NF.B.5.b
20 · Division Can Make Bigger	Working With Fractions	6.NS.A.1 5.NF.B.7.b

Student privacy

Students never sign in and never type in anything about themselves. Progress is stored in each device’s browser. There are no ads, no trackers and no third-party scripts on lesson pages. Read the privacy notice.

Keeping Slices free

Help keep Slices free for every classroom

There’s no school license and no paid version for students. If we’ve earned a spot in your lessons, a donation from you, your PTA or your school helps us keep it free and keep adding slices.

Ways to support Slices

Questions teachers ask

Is Slices aligned to the Common Core?

Each slice lists the Common Core State Standards it supports, mostly from grades 3 to 6 (3.NF, 4.NF, 5.NF and 6.NS). We don’t assume any particular curriculum, so the lessons work just as well outside the United States.

Do students need accounts?

No. Students can open any slice from a link without signing in, and their progress is saved in the browser on their device. There are no student logins to manage and no student data to collect.

Can I see my students’ progress?

Not yet. Progress stays on each student’s device, which keeps their data private. A student can show you their progress page, and the practice questions on every slice make good exit tickets.

What do I get with a teacher account?

The same free account anyone can make. It keeps your own progress in sync, and it opens challenge rounds, mixed practice and the Fraction Lab, where you can build any two fractions and compare them on the projector.

Does it work on Chromebooks, iPads and phones?

Yes. It runs in any modern browser and works with touch, a mouse or a keyboard alone. There’s nothing to install.

Is Slices accessible?

We’ve worked hard on it. Every model works with a keyboard, every picture has a text description, color is never the only signal, motion respects reduced-motion settings, and nothing is timed. Every slice also has a complete written explanation.