Interactives
Free science, maths, coding and thinking interactives to try right here, no account needed, no ads. Each one is shared by its makers under a free licence. Looking for something to read? Try the free books and guides.
Can't decide? We'll pick an interactive for you.
Projectile Motion
Fire a cannon and see how angle and speed change where things land.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Energy Skate Park
Build ramps for a skater and watch energy change form.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Forces and Motion
Push, pull and race carts to feel how forces work.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Friction
Rub two surfaces together and see the atoms heat up.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Balancing Act
Balance a see-saw with bricks, and find the rule behind it.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Density
Drop blocks in water and work out why some float.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Wave on a String
Wiggle a string and play with waves.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Pendulum Lab
Swing pendulums and test what changes their timing.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Masses and Springs
Hang weights on springs and watch them bounce.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Circuit Construction Kit
Build circuits with batteries, bulbs and switches.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Balloons and Static Electricity
Rub a balloon on a jumper and see the charges move.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Colour Vision
Mix coloured light and see what a person sees.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Lenses and Light
Bend light with lenses and mirrors.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Gravity Force Lab
Change two masses and measure the pull between them.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Gravity and Orbits
Move the Sun, Earth and Moon and see how orbits work.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
My Solar System
Design your own solar system and watch it run.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Build an Atom
Add protons, neutrons and electrons to make elements.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Build a Molecule
Snap atoms together into real molecules.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Molecule Shapes
See molecules in 3D and why they take their shape.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
States of Matter
Heat and cool atoms to turn solids into liquids and gas.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
pH Scale
Test everyday liquids and find out how acidic they are.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Natural Selection
Help bunnies survive and watch a population change.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Fractions Intro
Build fractions with pies, bars and cups.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Fraction Matcher
Match fractions that look different but are the same.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Area Builder
Build shapes from squares and work out their area.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Arithmetic
Quick-fire multiplication, division and factor puzzles.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Make a Ten
Add numbers by making tens.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Equality Explorer
Balance a scale to solve equations.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Number Line: Integers
Place positive and negative numbers on a line.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Graphing Lines
Draw lines on a graph and discover slope.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Waves Intro
Make water, sound and light waves and see what they have in common.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Sound Waves
Watch sound spread out, bounce around and reach your ear.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Wave Interference
Drop two sources of waves and watch them add up and cancel out.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Normal Modes
Hang a row of masses on springs and find the patterns they like to move in.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Fourier: Making Waves
Add simple waves together to build any shape you like.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Faraday's Law
Move a magnet near a coil and light up a bulb.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Magnets and Electromagnets
Play with bar magnets, then build an electromagnet from a battery and a coil.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Magnet and Compass
See how a compass needle answers to a magnet, and to the Earth.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Charges and Fields
Place charges and measure the electric field around them.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Coulomb's Law
Change two charges and the gap between them and feel the force.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
John Travoltage
Rub John's foot on the carpet and zap the doorknob.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Ohm's Law
Change the voltage and the resistance and watch the current respond.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Resistance in a Wire
Stretch and thicken a wire to see what changes its resistance.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Capacitor Lab
Build a capacitor and see how much charge it can hold.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Circuit Construction Kit: AC
Build circuits with an alternating current, plus capacitors and inductors.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Energy Forms and Changes
Heat up a block, boil water, and follow the energy as it moves.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Hooke's Law
Stretch and squash springs and find the rule for how hard they push back.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Collision Lab
Crash balls together and check what happens to momentum and energy.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Bending Light
Shine a laser through different materials and watch it bend.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Under Pressure
Dive into water and find out what pressure does at depth.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Buoyancy
Drop blocks into water and work out what makes them float or sink.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Blackbody Spectrum
Heat up an object and see the light it gives off change colour.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Greenhouse Effect
Follow sunlight and heat through the atmosphere and see what warms the planet.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Rutherford Scattering
Fire particles at an atom to find out what is inside.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Models of the Hydrogen Atom
Compare old and new ideas about what a hydrogen atom looks like.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Quantum Wave Interference
Send light, electrons and more through slits and watch waves appear.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Build a Nucleus
Pack protons and neutrons together and see which nuclei hold.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Kepler's Laws
Watch a planet speed up and slow down and see the laws of its orbit.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Gases Intro
Pump in gas, heat it, squeeze it and see what the particles do.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Reactants, Products and Leftovers
Make sandwiches, then real molecules, and see what gets used up.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Balancing Chemical Equations
Add molecules until both sides of the equation match.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Acid-Base Solutions
Mix strong and weak acids and bases and watch the ions.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Molarity
Add more solute or more water and see how the concentration changes.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Concentration
Pour in a coloured solution and see how strong it gets.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Beer's Law Lab
Shine light through a solution and see how much gets through.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Molecule Polarity
Change the atoms in a molecule and see where the charge piles up.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Molecules and Light
See which molecules soak up which kinds of light.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Diffusion
Open a gap between two boxes of particles and watch them mix.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Isotopes and Atomic Mass
Mix isotopes and see how the average atomic mass comes about.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
pH Scale: Basics
Try the pH of everyday liquids with a simple meter.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Neuron
Zap a nerve cell and watch the signal travel along it.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Function Builder
Feed numbers into a machine and work out the rule inside.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Proportion Playground
Paint, mix and stretch things and see which stay in proportion.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Ratio and Proportion
Match up ratios by moving the hands on a pair of sliders.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Unit Rates
Shop for apples, peaches and more and work out the price of one.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Number Compare
Compare numbers with blocks, a number line and the signs.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Graphing Quadratics
Drag a parabola about and see what its equation says.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Trig Tour
Spin around the unit circle and see sine, cosine and tangent as you go.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Vector Addition
Add arrows together and see where they take you.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Vector Addition: Equations
Add vectors, then match them to their equations.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Calculus Grapher
Draw a curve and see its derivative and integral appear beside it.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Curve Fitting
Drag a curve until it fits the dots as well as it can.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Least-Squares Regression
Drag a line through the dots and see how the errors add up.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Center and Variability
Explore means, medians and spread with piles of data.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Plinko Probability
Drop balls through the pegs and see a bell curve grow.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Build a Fraction
Make the fraction you are asked for from shapes and numbers.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Area Model Algebra
Use rectangles to multiply and factor expressions.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Energy Skate Park: Full
Build your own tracks and watch energy swap between moving, height and heat.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Faraday's Electromagnetic Lab
Play with magnets, coils and batteries to see how electricity and magnetism are linked.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Generator
Spin a turbine with water or a hand crank and light up a bulb.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Gravity Force Lab: Basics
Slide two masses about and watch how the pull between them changes.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Masses and Springs: Basics
Hang masses on springs, then try them on other planets.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Buoyancy: Basics
Drop blocks in water and see which ones float and why.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Atomic Interactions
Pull two atoms together and apart and feel the forces between them.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Circuit Construction Kit: DC Virtual Lab
Build circuits with real-looking meters, wires and bulbs, then try to break them.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Circuit Construction Kit: AC Virtual Lab
The AC version of the circuit lab, with capacitors, inductors and a scope.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Geometric Optics
Move a light, a lens and a screen about to see how images form.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Projectile Data Lab
Fire lots of projectiles and look at the spread in where they land.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Projectile Sampling Distributions
Fire projectiles in batches and see how averages settle down.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Quantum Coin Toss
Toss coins that follow quantum rules and compare them with ordinary ones.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Quantum Measurement
Measure quantum particles and see how the act of looking changes the result.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
States of Matter
Heat, cool and squeeze atoms and molecules to see solids, liquids and gases form.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Gas Properties
Pump in gas, change the temperature and size of the box, and watch the pressure.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Molecule Shapes: Basics
Build simple molecules and see why they bend and spread the way they do.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Gene Expression Essentials
Turn a gene on and off and watch a protein get made.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Membrane Transport
Watch what can get through a cell membrane and what needs help.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Area Model: Decimals
Multiply decimals by drawing them as rectangles.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Area Model: Introduction
Split up rectangles to see how multiplication works.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Area Model: Multiplication
Break big numbers into pieces and multiply with an area model.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Equality Explorer: Basics
Keep a scale balanced to learn what an equation really says.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Equality Explorer: Two Variables
Balance scales with two mystery shapes at once.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Expression Exchange
Rearrange and simplify algebra expressions by trading terms.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Fractions: Equality
Find different fractions that are worth the same amount.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Fractions: Mixed Numbers
Switch between mixed numbers and improper fractions with pictures.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Function Builder: Basics
Feed numbers through a machine and guess the rule inside.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Graphing Slope-Intercept
Change the slope and the intercept and see the line move.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Mean: Share and Balance
Share things out evenly to find the mean.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Number Line: Distance
Work out how far apart two numbers are on a number line.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Number Line: Operations
Add and subtract by hopping along a number line.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Number Pairs
Find the pairs of numbers that make a total.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Number Play
Make numbers with blocks, ten frames and a number line.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
Quadrilateral
Drag the corners of a four-sided shape and see which kinds it can become.
By PhET Interactive Simulations, University of Colorado Boulder, CC BY-NC 4.0
The Evolution of Trust
Play the trust game and see why people cooperate, or don't.
By Nicky Case (ncase.me), CC0
Parable of the Polygons
Nudge little shapes around and watch a mixed town split apart.
By Nicky Case (ncase.me), CC0
To Build a Better Ballot
Try different ways of voting and see who wins each time.
By Nicky Case (ncase.me), CC0
Loopy
Draw how things affect each other and watch the loops run.
By Nicky Case (ncase.me), CC0
The Wisdom and/or Madness of Crowds
Find out when crowds get smart, and when they follow each other off a cliff.
By Nicky Case (ncase.me), CC0
Double Slit
Fire particles at two slits and see them act like waves.
By Nicky Case (ncase.me), CC0
Fireflies
Fireflies flash in time with each other. See how it starts.
By Nicky Case (ncase.me), CC0
Contact Tracing and Privacy
See how tracing contacts can stop an outbreak, and what it costs your privacy.
By Nicky Case (ncase.me), CC0
Simulating the World (in Emoji)
Build a little world out of emoji and watch it play out.
By Nicky Case (ncase.me), CC0
Neurotic Neurons
See how brain cells pass signals along, and why they sometimes mix them up.
By Nicky Case (ncase.me), CC0
Learning and Games: A Confession
A short talk on how we really learn, and what games get wrong about it.
By Nicky Case (ncase.me), CC0
How to Remember Anything Forever-ish
A short comic on how memory works, and how to make things stick.
By Nicky Case (ncase.me), CC0
The Magnificent 2D Matrix
Play with a 2D matrix and see how it stretches, spins and squashes shapes.
By Nicky Case (ncase.me), CC0
Joy.js
Snap together happy little programs with a friendly editor.
By Nicky Case (ncase.me), CC0
It's a(door)able
A tiny one-minute minigame.
By Nicky Case (ncase.me), CC0
Attractor Landscapes
An interactive look at attractor landscapes, and why things settle where they do.
By Nicky Case (ncase.me), CC0
Particle Clicker
Run a particle detector, hire researchers and learn the physics as you go.
By CERN Webfest 2014 team, MIT licence
Keen
Fill the grid so the maths in every box works out.
By Simon Tatham's Portable Puzzle Collection, MIT licence
Towers
Place towers of different heights using the clues around the edge.
By Simon Tatham's Portable Puzzle Collection, MIT licence
Unequal
Fill the grid using the greater-than and less-than signs.
By Simon Tatham's Portable Puzzle Collection, MIT licence
Solo
A sudoku with extra shapes to try.
By Simon Tatham's Portable Puzzle Collection, MIT licence
Net
Turn the pieces to join every wire into one network.
By Simon Tatham's Portable Puzzle Collection, MIT licence
Untangle
Move the dots until no lines cross.
By Simon Tatham's Portable Puzzle Collection, MIT licence
Map
Colour a map so no touching countries match.
By Simon Tatham's Portable Puzzle Collection, MIT licence
Light Up
Place lamps to light every square without dazzling each other.
By Simon Tatham's Portable Puzzle Collection, MIT licence
Galaxies
Draw lines to split the grid into regions that look the same turned upside down.
By Simon Tatham's Portable Puzzle Collection, MIT licence
Pattern
Use the number clues to colour in squares and reveal a hidden picture.
By Simon Tatham's Portable Puzzle Collection, MIT licence
Mines
Clear the board without setting off any mines, using the numbers as clues.
By Simon Tatham's Portable Puzzle Collection, MIT licence
Loopy
Draw one single loop that goes round each number the right number of times.
By Simon Tatham's Portable Puzzle Collection, MIT licence
Pearl
Draw a loop through the black and white pearls, following the rules for each.
By Simon Tatham's Portable Puzzle Collection, MIT licence
Bridges
Join the islands with bridges so that the numbers add up and everything connects.
By Simon Tatham's Portable Puzzle Collection, MIT licence
Tents
Pitch a tent next to every tree, and keep the tents from touching.
By Simon Tatham's Portable Puzzle Collection, MIT licence
Slant
Fill each square with a slash so the numbers match and no loops form.
By Simon Tatham's Portable Puzzle Collection, MIT licence
Flood
Flood the board with one colour in as few moves as you can.
By Simon Tatham's Portable Puzzle Collection, MIT licence
Same Game
Click groups of matching blocks to clear the board.
By Simon Tatham's Portable Puzzle Collection, MIT licence
Guess
Crack the hidden colour code using the clues from each guess.
By Simon Tatham's Portable Puzzle Collection, MIT licence
Inertia
Slide a ball around the maze to collect every gem and dodge the mines.
By Simon Tatham's Portable Puzzle Collection, MIT licence
Pegs
Jump pegs over each other to clear the board until just one is left.
By Simon Tatham's Portable Puzzle Collection, MIT licence
Undead
Place ghosts, vampires and zombies so that what you can see in the mirrors adds up.
By Simon Tatham's Portable Puzzle Collection, MIT licence
Mosaic
Shade squares so each number counts the shaded squares around it.
By Simon Tatham's Portable Puzzle Collection, MIT licence
Group
Fill in a Cayley table so it follows the rules of a group. Tricky, and unfinished, so expect rough edges.
By Simon Tatham's Portable Puzzle Collection, MIT licence
Range
Shade squares so each number tells you how far you can see.
By Simon Tatham's Portable Puzzle Collection, MIT licence
Singles
Shade out repeated numbers so no row or column has a repeat.
By Simon Tatham's Portable Puzzle Collection, MIT licence
Palisade
Fence the grid into regions so each number tells you how many walls its square has.
By Simon Tatham's Portable Puzzle Collection, MIT licence
Filling
Fill the grid so each number sits in a group of exactly that size.
By Simon Tatham's Portable Puzzle Collection, MIT licence
Rectangles
Cut the grid into rectangles, each holding one number that matches its area.
By Simon Tatham's Portable Puzzle Collection, MIT licence
Signpost
Link the squares into one path by following the arrows from 1 to the end.
By Simon Tatham's Portable Puzzle Collection, MIT licence
Magnets
Place magnets in the dominoes so the clues around the edge are right.
By Simon Tatham's Portable Puzzle Collection, MIT licence
Dominosa
Pair up the numbers to make every domino in the set exactly once.
By Simon Tatham's Portable Puzzle Collection, MIT licence
Black Box
Fire rays into the box and work out where the hidden balls are.
By Simon Tatham's Portable Puzzle Collection, MIT licence
Cube
Roll a cube around the grid so the blue squares get picked up.
By Simon Tatham's Portable Puzzle Collection, MIT licence
Fifteen
Slide the tiles around until the numbers are in order.
By Simon Tatham's Portable Puzzle Collection, MIT licence
Sixteen
Slide whole rows and columns of tiles to put the numbers in order.
By Simon Tatham's Portable Puzzle Collection, MIT licence
Flip
Flip squares to turn the whole board one colour, with each flip changing its neighbours too.
By Simon Tatham's Portable Puzzle Collection, MIT licence
Netslide
Slide rows and columns around until the wires join into one network.
By Simon Tatham's Portable Puzzle Collection, MIT licence
Twiddle
Turn blocks of tiles around until the numbers are in order.
By Simon Tatham's Portable Puzzle Collection, MIT licence
Tracks
Lay train track from the start to the finish using the number clues.
By Simon Tatham's Portable Puzzle Collection, MIT licence
Unruly
Fill the grid with black and white squares, with no three in a row the same.
By Simon Tatham's Portable Puzzle Collection, MIT licence
Blockly Maze
Snap blocks together to guide a character through a maze.
By Blockly Games, Google, Apache-2.0
Blockly Bird
Program a bird to fly to its nest.
By Blockly Games, Google, Apache-2.0
Blockly Turtle
Draw pictures by giving a turtle instructions.
By Blockly Games, Google, Apache-2.0
Blockly Music
Write a tune with blocks.
By Blockly Games, Google, Apache-2.0
Blockly Puzzle
Match the animals to their parts by snapping blocks together.
By Blockly Games, Google, Apache-2.0
Blockly Movie
Draw a little animated film by writing a few lines of block code.
By Blockly Games, Google, Apache-2.0
Blockly Pond Tutor
Program a duck to duel other ducks, with hints to help you start.
By Blockly Games, Google, Apache-2.0
Blockly Pond
Write real code to win your duck duels.
By Blockly Games, Google, Apache-2.0
Flexbox Froggy
Write CSS to line the frogs up on their lily pads.
By Thomas Park (Codepip), MIT licence
CSS Grid Garden
Write CSS to water the carrots and grow your garden.
By Thomas Park (Codepip), MIT licence
Elevator Saga
Write JavaScript that moves the elevators and gets people where they are going.
By Magnus Wolffelt and contributors, MIT licence
Learn Git Branching
Practise git with a picture of your commits that changes as you type.
By Peter Cottle, MIT licence
Seeing Theory
Play with probability and statistics, from coin flips to regression, one picture at a time.
By Daniel Kunin and the Seeing Theory team, Brown University, Apache-2.0
Cube Composer
Chain little transformations together to turn a stack of cubes into the goal. It is functional programming as a puzzle.
By David Peter, MIT licence
Quantum Game with Photons
Steer single photons through mirrors and beam splitters to light up the detectors.
By Piotr Migdal, Patryk Hes and Michal Krupinski, MIT licence
Particle Life
Coloured dots pull and push each other with simple rules, and living-looking shapes appear.
By Hunar Ahmad, MIT licence
PathFinding.js
Draw walls and watch A*, Dijkstra and other search algorithms race to find the shortest way.
By Xueqiao Xu, MIT licence
Conway's Game of Life
Draw some cells, press play and watch simple rules grow gliders, guns and whole machines.
By Fabian Hemmer (copy.sh/life), BSD 2-clause licence
Neural Network Playground
Build a small neural network in your browser and watch it learn to sort the dots.
By TensorFlow Playground team, Google, Apache-2.0
BeepBox
Click notes onto a grid to write a chiptune. Your whole song lives in the link.
By John Nesky, MIT licence
Voice-change-o-Matic
Talk into your microphone and twist your voice with echoes, distortion and more.
By MDN Web Docs contributors, CC0
CSS Diner
Pick the right plates and bento boxes with CSS selectors, one order at a time.
By Luke Pacholski (flukeout), MPL-2.0
QuickQWERTY
Learn to touch type with short lessons, right in the browser.
By Susam Pal, MIT licence
Lenia
Smooth, living-looking creatures grow out of a continuous version of the Game of Life.
By Bert Chan, MIT licence
World Quizz
Name every country from its place on the map or its flag.
By Diana (World Quizz), MIT licence
2048
Slide the tiles, join matching numbers and see how far you can get past 2048. Good for any age.
By Gabriele Cirulli, MIT licence
A Dark Room
A text game that starts with a fire going out. Keep it lit, gather what you need and find out where the story goes. Ages 12 and up.
By Michael Townsend and Doublespeak Games, MPL-2.0
Genetic Cars
Watch random cars evolve over generations until they can drive over the hills. A neat look at how genetic algorithms work.
By Rafael Matsunaga (red42), based on BoxCar2D, zlib licence
Orca
Type letters into a grid and they come alive as little machines that make patterns and notes. Best for older students who like to tinker.
By Hundred Rabbits, MIT licence
jsfxr
Press a button and get a retro sound effect, then tweak the sliders to make jumps, lasers and coin pickups of your own.
By Chris McCormick, based on sfxr by Tomas Pettersson (DrPetter), Unlicense
Explain Git with D3
Type git commands and watch the commit tree change, so branches, merges and rebases finally make sense.
By Wei Wang, MIT licence
Proxx
Minesweeper in space. Scan the grid, work out where the black holes are and clear a safe path. Good for any age.
By Google Chrome Labs, Apache-2.0
PuzzleScript
Write simple rules and draw tiny pictures to make your own block-pushing puzzle game, then play it straight away. Best for ages 11 and up.
By Stephen Lavelle (increpare), MIT licence
Bitsy
Draw tiny pictures, build rooms and write dialogue to make a little game or story. No coding needed. Good for any age.
By Adam Le Doux and the Bitsy contributors, MIT licence
TIC-80
A tiny retro computer in your browser with a code editor, sprite and map editors and a sound studio, all in one. Best for ages 11 and up.
By Vadim Grigoruk (Nesbox) and contributors, MIT licence
KAPLAY
Change a few lines of JavaScript and watch your game change next to it. A friendly way to start making games in code. Best for ages 11 and up.
By KAPLAY Team, MIT licence
Pyxel Code Maker
Write a few lines of Python and watch a retro game run next to your code, with sprite and sound editors on hand. Best for ages 11 and up.
By Takashi Kitao, MIT licence
Hextris
Turn a hexagon to catch the falling blocks and match three or more colours to clear them. Quick to learn, hard to put down. Good for any age.
By Logan Engstrom, Garrett Finucane and the Hextris contributors, GPL-3.0
Untrusted
Escape a machine maze by reading and rewriting the JavaScript that runs the world around you. Best for ages 12 and up, and some JavaScript helps.
By Alex Nisnevich and Greg Shuflin, CC BY-NC-SA 3.0
Twine
Write interactive stories where readers pick the path, by linking little boxes of text together on a map. No coding needed to start. Good for any age.
By Chris Klimas and the Twine contributors, GPL-3.0
Snap!
Build programs by snapping blocks together, like Scratch with extra powers: make your own blocks, use lists and even write functions that take functions. Good for any age.
By Jens Moenig, Brian Harvey and the Snap! contributors, AGPL-3.0
3D.CITY
A city builder in the style of classic city sims, in full 3D. Zone land, lay roads and power, and watch your town grow, with fires, floods and the odd monster to handle. Good for any age, and it needs a reasonably modern computer.
By lo-th, built on micropolisJS by Graeme McCutcheon, GPL-3.0
micropolisJS
A city builder in the style of classic city sims. Zone land, lay roads and power lines, set taxes and see if your town grows or gets flattened by a monster. Best for ages 8 and up.
By Graeme McCutcheon, GPL-3.0
Chess Trainer
Learn chess with short lessons, solve puzzles, drill openings and play a computer opponent that adjusts to your level. Works offline. Good for any age.
By Real-Fruit-Snacks and the Chess Trainer contributors, GPL-3.0
Lemonade Stand
Run a lemonade stand, find the price that really makes money, then grow it and learn how companies and share prices work. No real money anywhere. Best for ages 9 and up.
By Kartikeya Goel, MIT licence