Life on the Refrigerator Door by Alice Kuipers
R- 1? (I don't remember there being much of anything in it.)
This is a very quick read (I think it took me an hour or less) because it's written entirely in notes that mother and daughter leave on the fridge. Some are simple requests to stop and pick something up from the store, others are thought-provoking and touching expressions of love. It's poignant and I almost even cried (which is saying a lot... nothing makes me cry).
I'd recommend this to anyone, but I think mothers and teenage girls will probably get the most out of it.