Credits
Last updated 7 October 2026
Some of the pictures Saitama teaches with are textbook figures drawn by experts and shared freely. We use them so the parts of a heart or a cell are always in their true places. Thank you to the people who made them.
Pictures
For each one we removed the original labels and made an outline version for the whiteboard to draw by hand; the tutor writes its own labels. Our changed versions are shared under the same licence as the original.
- The human heart cut open from the front, showing its four chambers, valves and great vessels, by Wapcaplet, Yaddah and others (Wikimedia Commons). Original on Wikimedia Commons, CC BY-SA 3.0.
- A plant cell cut open, showing its organelles, by Mariana Ruiz Villarreal (LadyofHats). Original on Wikimedia Commons, Public domain.
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Molecules
The structures of molecules come from PubChem, the open chemistry database of the US National Library of Medicine.
Circuits
The symbols in the circuits the tutor draws (resistors, transistors, op-amps, logic gates and the rest) take their shapes from Schemdraw, by Collin J. Delker. Source, MIT License.
Where each part and wire of a circuit goes is worked out on our server by diagen, by Chaoos-404. Source, GNU General Public License v3.0.