7. Matthew read 1/8 of a book. Then, after an hour's break, he read 3/8 of the book. How much of the book did Matthew read?

This is pretty much a normal addition problem. he read 1/8 of a book and 3/8 of the book--the wholes are the same. After going through the previous tricky problems, I often have people who think it's a problem that it doesn't specify that he didn't re-read the first part of the book in his second reading session. I find this scenario much less likely than the overlap in problem 1 (students getting A's on both tests) so I gave full credit to the student who submitted this problem, and did not ask for any revisions. If you wished to revise it, you should make sure that you do it by saying:

Good revision: Matthew read 1/8 of a book. Then, after an hour's break, he read another 3/8 of the book. How much of the book did Matthew read?

and not

Bad revision: Matthew read 1/8 of a book. Then, after an hour's break, he read 3/8 of the rest of the book. How much of the book did Matthew read?

since this second revision changes the whole, and the problem changes from an addition: 1/8 + 3/8 to something more complicated: 1/8 + 3/8 x 7/8.