Pie Lab
Young students can follow a pattern without seeing the rule inside it. In Pie Lab they weave a pie top over and under by hand, then find the one rule that weaves it for them, and write rules that bake it while they watch.
Using this with a class? Make a free class and add your students yourself: each gets a username and password, with no email or Google account needed. Or give them one join code. Using Google Classroom? Post the link there; with a free class, the link also puts each student in your class, so you see their work. mytekDev is also available from the Google Workspace Marketplace, so your school's Google admin can install it for everyone.A first lesson: One period: weave the top, flip a crossing and find the rule, then bake a cherry pie with two oven rules and see which ribbon it wins. A second period for the sheet, the puzzles and a blueberry pie that needs more than one change.
Set up a free class Share to Google ClassroomWhat a student actually does
A cherry pie with a woven lattice top sits on a wooden board, in 3D, and turns when it is dragged. Each strip goes over, under, over. Clicking any crossing flips it, and the readout under the pie says the weave is broken: some strip now goes over two in a row. A grid of strip numbers, counted from 1, shows every crossing. Choosing My rule turns the weave into a sentence with blue choice words: strip i goes over strip j when i + j is even. Change even to odd, or i + j to every 2nd, and the pie weaves itself again in a new pattern.
Then it goes in the oven. The edge browns first, because hot air reaches it from more sides and there is no wet filling under it. The filling bubbles through the gaps. The student decides when to take it out, or writes up to four oven rules as sentences: "When the edge is golden, right away put foil on the edge", "When the filling bubbles, wait 5 minutes, after that take it out". A rule happens at the moment its when comes true, and the card draws a timeline of when each rule happened and names any rule that never did.
A judge looks at every pie that comes out. A white ribbon means done in the middle with nothing ruined, a red ribbon adds a golden edge and top, and the blue ribbon also needs the pie out within a few minutes of just right, a bottom that is not pale and an edge that matches the top. By hand the blue window on a cherry pie is about a minute; a rule gets it every time. A burnt pie, one that bubbled over or cracked, gets an honest line and no ribbon. Then the student cuts a slice: cut hot, the filling runs onto the plate; cooled 4 hours, it holds its shape. There are four pies, a sheet to hand in, eight puzzles and a teacher setup.
The weave as a rule. Each cell is one crossing with its two strip numbers added up: an even sum means the strip going front to back is on top. Change even to odd and every crossing flips.
What they are learning while they work
Nothing here is presented as a lesson. This is what the activity is made of.
| What the student does | What it is |
|---|---|
| Clicks a crossing and sees the strip now goes over two in a row | A pattern has a rule. Over, under, over is not luck. Every crossing follows the same rule, and breaking it at one crossing shows up all along the strip. |
| Adds the two strip numbers in a grid cell: 2 + 3 = 5, odd, so under | An algorithm from even and odd. One short rule decides every crossing. Students check it by hand on a few cells, then trust it for all of them. |
| Changes "even" to "odd" and watches every crossing flip | Changing an algorithm changes the result. The same rule with one word changed makes a different pie. Comparing woven, laid and two over two is comparing algorithms for the same job. |
| Watches the dough readout go up when strips are added | Values a program keeps track of. The number of strips and the length of dough change together; the dish size stays put because nothing changed it. |
| Writes "When the edge is golden, right away put foil on the edge" | Events and conditionals. A rule has a when and a do. It waits, and happens at the moment its when comes true, the way a when block works in block code. |
| Writes "wait 5 minutes, after that take it out" and compares it with right away | Sequence. The wait comes before the action. Right away takes the pie out before the filling has thickened; waiting first gets it done. |
| Reads "Rule 2 never happened" and finds a when that cannot come true | Debugging. "The filling is set" never happens in a fruit pie, which bubbles instead. The timeline shows exactly which rule did nothing, so the bug can be found and fixed. |
How to tell whether it landed
Ask, and let them show you. A student who has understood it can answer these without help.
- Strip 3 crosses strip 4. Using "i + j is even", which strip is on top? How do you know?
- Why does "i is even" not make a woven top?
- Your rule says put foil on when the edge is golden. The edge stays golden. Does the rule happen again?
- Which takes a thicker pie out: "when it bubbles, right away take it out" or "when it bubbles, wait 5 minutes, after that take it out"? Why?
- Your pie got a red ribbon. What one thing would you change to win the blue?
- One of your rules never happened. How would you find out why?
Use it in your subject
Not a technology class? Then the app is how students show what they learned in your unit. More projects for every subject.
Elementary computer science
Grades 3 to 5: algorithms from a pattern (the weave rule), events and conditionals (the oven rules), sequence (wait, after that) and debugging (the rule that never happened). Block-code ideas without blocks, in sentences a nine-year-old can read.
Math
Even and odd numbers in a real job: every crossing is a sum to sort. Strips are numbered from 1, so the first crossing is 1 + 1 = 2. Grades 6 to 8 also get floor(i/2), i times j and multiples of 3.
Science
Heat and change you cannot undo: the edge browns first, a metal dish heats the bottom faster than glass, steam needs a way out, and a filling sets as it cools. The oven is the app's own model, and the app says so.
Homeschool and co-ops
Weave a lattice from paper strips at the table first, by the same rule, then bake the pie in the app. A real pie, if you make one, follows a real recipe.
Practical notes
- AgesGrades 3 to 5 are the home ground: rules are sentences of choice words, strips are numbered from 1, and the even-and-odd rule is the only math. Grades 6 to 8 switch on the rule as math (floor, multiples of 3) and the oven's own words for its model.
- TimeOne period to weave, find the rule and bake a pie with two rules. A second for the sheet, the puzzles and the harder pies.
- EquipmentA computer or Chromebook with a modern browser. Nothing to install. A projector for Big screen, where the space bar bakes and takes the pie out. A printer if you want the sheet on paper.
- CostFree. The app has no paid tier.
- PrepBake one cherry pie yourself with the two rules from the try box, about five minutes. Then flip a crossing and change the weave rule to odd. That is the whole demo.
- In a groupOpen Setup in the app's header: the grade level, which questions the sheet asks, up to ten of your own, and a printed answer key that lists the rules that win the blue ribbon for each pie.
For co-ops, microschools, and classrooms
Set it up once in Setup and hand the project out as the starter; the setup travels with it. With a free account the students' pies come back to you as saved projects, with their rules, their ribbons and their sheets.
Common questions
Is it free?
Yes. Pie Lab has no paid tier, and it can be tried right on this page without an account.
Is this coding?
Yes, without a programming language. The weave rule is an algorithm, and the oven rules are events and conditionals with a sequence, written as sentences of choice words. They are the same ideas as when blocks and if blocks in block code, at a reading level for grades 3 to 5.
Is the oven real?
No. It is the app's own small model of heat, and the app says so. The causes are real ones (the edge browns first, metal heats the bottom faster than glass, steam needs vents, fruit fillings set as they cool), but the times and colors are Pie Lab's own. To bake a real pie, follow a real recipe.
Why is the blue ribbon so hard by hand?
On purpose. The pie has to come out within a minute or so of just right, which is hard to catch on a fast clock and easy for a rule. Students reach for a rule because they want the ribbon.
Why can't a pie with no ribbon be shared?
A burnt or overflowing pie can be funny, and the app does not want that to be the thing students collect. When a student shares a pie with no ribbon, Pie Lab asks them to bake one that wins a ribbon first.
Which pies are in it?
Cherry, apple, blueberry and pumpkin. Cherry and blueberry start with a woven top, apple with a full top and vents, pumpkin open with no top. Each wins its blue ribbon a different way.
Does it run on Chromebooks?
Yes. It is 3D in the browser with nothing to install, it draws a lighter picture on a slow machine, and it has a Big screen mode for a projector.
Still have a question? Ask us, and a person will write back.
Where to go next
Start with Pie Lab
Trying it costs nothing and takes about five minutes. An account is what makes the work last.
Pie Lab is one of the making apps on the platform. Its oven is a model with its own numbers, every fact it states was checked against baking sources, and it never gives a recipe.
Page last reviewed November 2026.
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