Scavenger Hunt

Hello.

I've created a scavenger hunt of sorts for a training I'm working on, where the user has to click certain hot spots to identify the safety issues. Since they can't really tell how many issues exist in the image total, I wanted to create an art asset that shows them how many things they need to find, and, once they've clicked one, fill in one of those icons (currently a star).

So, they find object 1, a star fills in. Find object 2, the other star fills in. It should be setup so that star 1 fills in regardless of which safety item they select first.

I'd love some advice on how to go about doing that. 

Thanks.