Translation:What's written on the blackboard? I can't see it clearly.
You are right. When看followed by书, it means "read". However, 看can also mean see, look and watch. When 看is followed by 电影 (movie), it means watch movie. When看is followed by 一眼, it means "have a glance". e.g. 他看了一眼那个女孩，然后快步走开。He had a glance at that girl and quickly walked away.
Sure 看书 means read a book. But it has the same meaning with 读书. But in English you can't say see a book to express 看书.
"What's written on the blackboard? I can't see clearly." Exactly the same but without "it". Still makes perfect sense to me as an English speaker.
It's still good grammar but has a different meaning. Without it, it implies you generally have bad eyesight, whereas with it, it just means you can't see what's on the board.
So both should be accepted. I only ever used "blackboard" but I recognize that others use "chalkboard".
Mine says "What has written on the blackboard?" as a translation. That's not even correct English, haha. Should be "What is written on the blackboard?"
You can mark those as "not natural" and the idea is that they will get around to fixing them.