Great idea! I'm not sure what text was allowed for some of the answers: greater than worked but smaller than didn't; I tried leftsquarebracket and it didnt work etc. Perhaps you can make it so that the possible things you type appear with the answers? Also, I missed all the arrows but I don't think those are present in that position on many keyboards. Perhaps you could colour differently the cells with no answers. Well done!
this was a really cool quiz, except that I still don't know what the names of the symbols I didn't know are :/ (namely, ~ (tilde didn't work), `, and |)