Try it in 60 seconds
Most apps explain a concept. letsgye hands you the model to operate. Here are a handful, straight from real lessons, from Wi-Fi to problem solving, creativity, and seeing a problem many ways. Touch them.
Nothing you do here is sent anywhere. No sign-in, no install, no tracking. Every simulation runs in your browser, so go ahead and poke at it.
Why Wi-Fi drops through walls
Move the router, switch the band, and watch the signal fade through brick. Radio physics you can steer.
5 GHz is fastest up close, but watch it fade as walls get in the way.
How the internet survives a noisy line
Send a message and watch checksums catch the corrupted bits and ask for a resend. This is how files arrive intact.
Each byte has a 30% chance of getting scrambled in flight.
Waiting for a packet…
Press Send to start a transmission.
message = "HELLO"packet = message # no checksum yetsend(packet)# at the receiver:received = receive()print(received) # no way to know if it's right
Try this: turn Checksum ON and crank noise to 60%. Most sends will fail, and now the receiver actually notices.
Then turn Retry ON. Watch the network try again until the message arrives clean. That tiny loop is the heart of TCP, the protocol your phone uses billions of times a day.
Ohm's law you can feel
Turn the dials and watch the voltage split. The same rule behind every dimmer, sensor, and charger.
= 5 x 10000 / (10000 + 10000)
= 2.500 V
Vout scales with R2 / (R1+R2). At R1=R2, Vout = Vin/2; R1 much greater than R2 approaches 0; R1 much less than R2 approaches Vin.
Why you forget, and what fixes it
Watch memory fade on the forgetting curve, then see how a well-timed review snaps it back. The science the whole app runs on.
With no review, retention crashes to about 14% by day 30. Turn on spaced reviews to see the curve hold up.
How a chart can lie
Slide the y-axis and watch the very same numbers look like a crisis, then like nothing. Spot the trick once and you see it everywhere.
The right chart starts at 100, not 0, so the same +3% now looks huge: the Q2 bar looks 2.0x the Q1 bar, and Q4 looks 4.0x. The data did not move, the axis did. The eye reads bar heights, and chopping the axis stretches the gap.
Watch a problem get solved
Pick a strategy and watch it search the maze. Flood touches everything; Smart aims with a heuristic and reaches the goal through far fewer cells. Tap the grid to add walls and it re-plans on the spot.
The same idea routes your GPS, plans a chess engine, and moves a delivery fleet. A good heuristic is why a machine can weigh millions of options and still answer in a blink. The skill: search smart, not hard.
Grow an idea in every direction
Invent uses for an everyday object and watch them bloom. It counts how many, and how many different directions, then fuses two into something new. Creativity you can see, not a personality quiz.
Guilford's classic test of divergent thinking: fluency (how many) and flexibility (how many directions). It never scores an idea "good"; you go wide first, then choose. Fusing two is where novelty is born.
Train creative thinking for realSee one problem six different ways
Turn the lens on the same situation and watch it become a different problem each time, with the hidden assumption each view exposes. The skill behind good design, judgement, and invention.
Pick a lens. Watch the same problem become a different problem.
Each lens hides a different assumption. See at least 4 before you pick a side.
Kill the idea that would fail, cheaply
Every new idea rests on hidden assumptions. Spend a small budget to test the riskiest one first, watch the doubt collapse, and see what the same lesson would have cost after you built the wrong thing. Zero to one, de-risked.
Real value-of-information: the drop in the doubt bar when you test an assumption is its weighted entropy (the information a clean test reveals), and a test is worth the fatal cost it saves you times the chance it fires, minus what the test costs. The cheapest, most load-bearing, most-likely-wrong assumption is almost always the one to test first.
Train zero-to-one judgment for realThat is one minute. There are hundreds more.
Every lesson is built like this: an accurate model you operate until the idea clicks, then spaced review so it sticks. Zero to expert, offline, and private.