（テキストや解答用紙に）落書きしない。って英語でなんて言うの？

1. Neat and tidy- can be used to describe something being clean and neat.

2. Not allowed- this means that you should not do something or should stop doing something

I hope this helps :)

Messing up = making something untidy or damaging something.
My mother always kept her recipe books nice and tidy in the bookcase.
(In this case 'nice' has the meaning of undamaged or pristine)

"Do not"
Means they must not do this.

"Doodle", "scribble", "draw" are all different words to explain graffiti.

"Please only write the answers on your answer sheet." Tells the students that the only writing that must be on the answer sheet in their answers.

This may help try give your children guidance in what they are allowed to do and what they are not allowed to do. Been firm but also showing the correct action.

1. No scribbling on your books please.
   You can simply say this sentence, to let your children know that if they write or draw untidily, they will be disciplined.

   2. Please keep your book clean and tidy.
      Clean and tidy means neat and well organised.

All three cautions will suffice. Politeness will go a long way in making the children understand. It also teaches them how to behave towards other people.

If you want to tell your children not to draw on the books and answer sheets you can say something like “do not draw on any of the books or answer sheets please.” or “don’t draw on the answer sheets and books.” You can say something like this in a stern way so they know you are being serious.