Add a 3 tiles large blackboard. Nothing less, nothing more.
The texture is the original Blackboard up-scaled for a less messy result, but It's still messy AF, sorry, i'm at child level when it comes to drawing something :(.
--- Compatibility ---
* Rimworld < 1.5, i don't know, try and tell me. I set Biotech as required but i don't know if that's necessary.
* CE ? It's compatible with Children Expanded yup. And for Combat Extended, well, no it's not patched and i don't think you would have to as your pawn will not hit someone with the blackboard. It would be cool if they could throw chalks, tho.
* Life Lessons : I patched it on my end, i will ask the OG mod author if they could integrate it directly.
* Other mods : There is no reason it would not work, it's literally just an added ThingDef.