For grown-ups

What this is

A real circuit simulator — the same solver the rest of Ohmsville runs — with the parts drawn as blocks a child snaps together by tapping two of them. Nothing is pretend: the light comes on because the current through it is real, and the resistor gets hot because 9 V across 100 Ω really is 0.81 W.

What checks the work

One request per Check it press, to Ohmsville’s own server. It carries readings taken from the simulator and the project’s own text — the title, the goal, the explanation. A Claude model reads those readings and answers one thing: did it work. That yes-or-no is all that comes back into the page.

Nothing the model writes is shown to a child. The encouragement and the hints in this section were written by a person and chosen by a table of conditions over the same readings.

What this section does not do

No sign-in, no account, no email, no password, no code. No camera and no microphone. No chat: there is nothing here to type into, and nothing a child writes goes anywhere, because there is nowhere to write it. No adverts, and no links off this site.

Where the progress lives

This browser, in its own storage. Clearing site data clears it. Nothing is on a server unless the child later claims a player code on the main bench, which is a grown-up’s decision on a grown-up’s page.

The safety lesson

This is nine volts in a simulator. Real mains electricity is not a toy and is never a project. A battery shorted with a coin or a paperclip gets hot enough to burn.

The resistor in every one of these builds is the thing keeping the light from cooking. One project here — Let the smoke out — deliberately removes it, so a child can see what happens, safely, once. That is why it is there.