Organic Molecule Builder
Pick a homologous series, choose the chain length and move the functional group to discover structural isomers. Switch between the displayed formula you draw in exams and a 3D-style ball & stick model.
Reaction Animator
Watch bonds break and form. Press play, or drag the slider to scrub through the reaction one step at a time.
Atom Builder
Add protons, neutrons and electrons to build any of the first 20 elements, their isotopes and their ions. Watch the electronic configuration change shell by shell.
Python Challenges
Write real Python in your browser. Press Run to try your code, then Submit to check it against our hidden tests. Your progress is saved on this device.
Program input (one line per input() call)
Binary & Hex Playground
Flip bits to build numbers, shift them, add them and see two's complement in action. Then test yourself in challenge mode.
Logic Gate Simulator
Click the input switches to turn them on and off. Green wires carry a 1. Click any row of the truth table to jump to that input combination.
Logic expression
Algorithm Visualiser
Watch standard sorting and searching algorithms run step by step, with the pseudocode line being executed highlighted as it goes.
Packet Switching Simulator
Type a message and send it. It is split into packets that each find their own route through the routers, arrive out of order, and are reassembled using their packet numbers.
Motion Graphs
Set the car's starting speed and acceleration, then press play. The distance–time and speed–time graphs are drawn live as it moves.
Distance–time
Speed–time
Wave Machine
Compare transverse and longitudinal waves. Follow the red particle: it only vibrates about one spot while the wave's energy travels along.
Circuit Lab
Two lamps, one battery. Wire them in series or parallel, change the voltage and resistances, and watch the current flow and the lamps glow.
Refraction & Total Internal Reflection
Change the angle of incidence and the material. Go from glass to air and push past the critical angle to see total internal reflection, the physics behind optical fibres.
Graph Explorer
Drag the sliders to see how each number in the equation changes the graph. Pin a graph to compare it with the next one. Hover over the graph to trace coordinates.
SOHCAHTOA Triangle
Change the angle and the hypotenuse to see how the sides relate. Then try the practice questions, rounding answers to 3 significant figures.
Transformation Studio
Choose a transformation and its details, then press Transform to watch shape A move onto its image A′. The full description is written for you, exactly as the examiner wants it.
Probability Simulator
Run the experiment many times. As the number of trials grows, the relative frequency (green bars) gets closer and closer to the theoretical probability (dashed lines).