This is book number 5 in the Baby-Sitters Little Sister series.
Say Cheese!
Karen has to get glasses -- two pairs! One pair for reading and one for all the time. Karen does not want glasses. Her school pictures are going to be taken soon! But Karen has to . . . so she picks out some pretty pink and blue ones. Karen thinks she looks very grown-up.
Then Yicky Ricky at school calls her Four-eyes. If Karen wears her glasses for the school picture, Ricky will make fun of her. But Karen is not a wimp! Glasses or no glasses -- that Ricky is going to get it!