A mother decides to teach her son about a letter each week. She will choose a letter from the name of the day. For example, on Saturday she might teach about the letter S or the letter U, but not the letter M.

1. What letters are possible to teach using this method? (There are 15.)
2.What 4 letters that can't be taught using this method?
3. On Tuesday, the mother writes the word on a piece of paper and cuts it up so each letter is on a separate piece of paper. She mixes up the papers and picks one. What is the probability that she will choose the with the letter Y? Explain.