Issue is mainly that gifs are often huge and with the small chat size, this could easily make it so people are not easily seen in chat.

I don't see how this would be useful, because people can actively choose to grade homework themselves? Why does there need to be this function?

I believe riddles are already ignoring cases, but anagrams makes sense why it is case sensitive, as you see the letters that you need to use.

There isn't

It is pretty easy for the teacher to find out who, by knowing the week and year of the asssignment.

I agree that the feature is unnecessary 

Wow, I never thought people would do this, I didn't event think of it as a possibility

This is about chat? I am confused reading your message, because it feels like you explain it poorly.

Are you asking for messages to disappear after a specific number of messages have gone through? You are saying that it saves the messages, but that is only true if you don't refresh the page. If you later on try to look back in chat, you don't see old messages after a certain amount of messages.

There could be made handling for the messages to be removed from chat after a specific amount of time, but truly 20-30 messages seem very little, but it isn't that much of an issue. If you experience lag, perhaps just reload the page.

Removing messages also makes it harder to monitor chat, if you get notified about behavior and wasn't there in time.

Isn't there already that when you start grading?

That is good, but you still have to spend your time on sending the gifts and depending on the site, that can be incredibly time demanding.