I have in column A a set of words: rain, wait, train,....

I have in column B a set of sentences: I played in the rain, I wait for the bus, I want to go on a train,...

It's for a spelling quiz.

I want to replace the word from column A with a $.

If I use the substitute formula =substitute(B1, A1, "$")

I get the sentence from B1

If I use the substitute formula =substitute(B1, "rain", "$")

I get what I want - the sentence "I played in the $."

Any suggestions?