For teachers

The net your students draw
folds up right in front of them.

Kyoten is a 3D puzzle where students look at a model solid, draw its net on a grid, and fold it up in 3D. It turns the nets of 3D shapes from geometry class into something students can check with their own hands. Whether the drawn net folds into the same shape as the model is checked automatically.

Try the 1-minute practice problem See the teacher screens in a sample class →All 11 nets of a cube

No sign-up or install

Just open kyoten5555.com in a browser. Students can play without entering a name or email.

Works on tablets and computers

Runs in the browser on school devices such as iPad, Chromebook and Windows. Works with a finger or a mouse.

Instant feedback

Students fold the net they drew; if it matches the model, it's cleared. When it's wrong, the folded shape shows them why.

Easy → hard

6 levels of difficulty, A to F. A is cubes and cuboids. Strong students can move on to harder shapes like L-shapes and stairs.

Auto-fold available

After drawing a net, the “Auto fold” button folds it one face at a time and checks it. Students who find the folding controls hard can focus on drawing nets.

Concave shapes made easy

With the “Pen” tool, students tap the corners of a shape in order to draw L-shapes and other concave faces as one piece.

Classroom & tutoring plans (for schools, tutoring centers, private tutors and math clubs)

Create classes and see homework and progress in one place

Join with just a code
Students enter a code, a name and a 4-digit passcode — no email or login. They can keep going as the same student on another device, like at home and at school.
A ranking just for your class
Names are visible only to the teacher and classmates. Real names never appear site-wide.
Each student's progress
See at a glance which problems each student cleared, how many tries it took, their times and when they last played. Export to CSV.
Assign homework
Pick problems from difficulty A–F and assign them with a due date — or let it auto-pick for you. Give it to the whole class or only to the students you choose.
Reports for parents
Make a one-page report for each student — days active, homework progress, newly cleared and in-progress problems, plus a note from you. Print it or save it as a PDF to send.
Live mode
Put who has solved what on the classroom screen. It refreshes every 10 seconds, which makes the last 10 minutes of class exciting.
Printouts
Print homework solids and grids as A4 worksheets. Students can draw on paper and then fold it on the site to check.
Per-problem analysis and notices
See each problem's clear rate and which students are stuck. Post notices from you on students' pages.
Class tasks
Give tasks to do right there in class, separate from homework. A ✓ appears on your screen the moment a student finishes folding.
Exam-style nets
Fold nets with triangle and trapezoid faces (solids that fit in a cube, cut cuboids) in 3D one face at a time. Generate as many similar problems as you like at the difficulty you choose.
Each student's record and solution replays
Click a student's name for a detailed record. Replay the nets they drew — cleared, failed or abandoned — from drawing to folding.
Check the student view
From your teacher screen, see exactly what students see.

Until March 2027

Free

Every class is free as part of our monitor program · it never switches to paid automatically

From April 2027 · per class · pick by number of students

Tutoring plan 5

Up to 5 students · private tutors & small groups

¥1,980 / month

or ¥19,800 / year (2 months free)

Create a class Ask about it

Tutoring plan 10

Up to 10 students · private tutors & small groups

¥2,980 / month

or ¥29,800 / year (2 months free)

Create a class Ask about it

Classroom plan

Up to 40 students · schools & tutoring centers

¥9,800 / month

or ¥98,000 / year (2 months free)

Create a class Ask about it

Pay by card; we can also issue invoices. You can change plans when the number of students changes.

Sample · classroomA class of 12 studentsProgress, class tasks, net folding, live mode, printouts and the student view→Sample · tutoringPrivate tutoring, 3 studentsDifferent homework for each student, and a one-page report for parents→

No sign-up needed. Students and records are made up.

Create a class for free (until March 2027)Ask us / get a quote

As before, you can also use it in class without creating a class (free). Students join at kyoten5555.com/join.

Example lesson (45 minutes)

1
Intro5 min
Put the “11 nets of a cube” page on the big screen and show nets folding into cubes. Look at the shapes that don't make a cube too.
2
Practice10 min
On their own devices, students do “How to play (1-minute practice)” and learn how to draw a cube net and fold it.
3
Challenge20 min
From the problem list on the home page, students work on difficulty A (cubes and cuboids). Fast finishers move on to B and up.
4
Wrap-up10 min
Share nets that didn't fold and sum up the rules: “at most 4 in a row”, “no 2×2 block”, “opposite faces skip one”. The net quiz (10 does-it-fold questions) is a good check.

Great on the big screen too

On the “11 nets of a cube” page, every net folds into a cube with one button. After folding you can drag to rotate it, which is handy for checking opposite faces.

Open the 11-nets page →

Learning pages for class

For young kids · NEWNet Play (a game for kids) →6 stages: does it make a box? → the missing face → opposite faces → dice → build it yourself. Kids pick up the ideas behind nets while collecting stars and stickers, and every answer folds up so they can check it.

All 11 nets of a cube →

Fold every shape with a button. Great as an intro.

Net quiz →

Does it fold into a cube? 10 questions, each folds up after you answer.

Opposite faces & dice →

Tap to find the opposite face. Includes dice problems (opposite faces add to 7).

Nets of a cuboid →

Matching faces are color-coded, and you can check that joined edges have the same length.

Before you start

Records and names: When students play without logging in, their records are saved per device and browser under a name like “Guest-xxxxxx”. No name or email is needed. Opening it again on the same device and browser picks up where they left off.

Rankings: Clear times and ratings appear in rankings other users can see (guests show as “Guest-xxxxxx”). If students sign up and choose a name, please remind them not to use their real name. Students in a classroom-plan class appear by their class name only inside the class, and as “Guest-xxxxxx” in site-wide rankings.

Contests: Contests (competitions where everyone solves the same problems at a set time) are only for registered users. In class, please use regular problems or the daily problem.

School networks: The site connects to an external database to save records. If problems don’t load because of web filtering, please check with your IT staff.

FAQ

Q. What ages is it for?: We recommend it from the grades where students learn nets of cubes and cuboids (around ages 9–10). Difficulty A is cubes and cuboids, so beginners can jump in. The hardest problems puzzle middle schoolers and adults too.
Q. Does it work on smartphones?: Yes. But drawing nets is easier on a bigger screen, so tablets or computers are best for class.
Q. Does a mirror image (flipped shape) count as correct?: No. It's only correct when it folds into a solid facing the same way as the model.
Q. Can it help with competitive entrance-exam prep?: With the classroom plan's “net folding (exam style)”, students fold nets with triangle and trapezoid faces in 3D to check them. These are original problems inspired by the “solids that fit in a cube” and “cut cuboids” often seen at top Japanese junior high schools such as Nada and Kaisei (not actual exam problems).
Q. Can I check during class whether everyone has finished?: Post a “class task” with the classroom plan and a ✓ appears on your screen each time a student finishes folding (refreshed every 8 seconds).

Questions and requests

Send questions about using it at school, feedback from your lessons, or problems and features you’d like via Contact & feedback.

Try one problem yourself first.

The 1-minute practice problem shows you how it works.

Try the practice problem All problems