What version of FileMaker do you have? FileMaker 13 offers a new option that is very simple to use. There are other methods that are a bit more complicated, but can work for older versions of FileMaker.
FileMaker Pro 13
In the Inspector's Data tab, there's a new option "Hide Object When" in FileMaker 13. You can enter a calculation expression there (just like a conditional format expression), that causes the selected layout object to be invisible if the calculation evaluates to return True.
So if the field in which the teacher enters "yes" is called YourTable::Present, you might enter this as your "Hide Object When" expression:
YourTable::Present = "No"
What's not clear from your initial post is what should happen if this field is empty--such as before the teacher has selected either "yes" or "no" for that field. If you want the fields to be invisible if the field is empty:
YourTable::Present ≠ "Yes"
Thank you so much for your help. I used the exact same solution and I got what I wanted. Thanks for your help!