The mayor joined the students at Children's Playhouse in South Philadelphia for snack time and read them a book.
Some of the kids are in class because of the program that provides quality education to young children for free.
The program, which started a week ago, is being paid for by money raised through the city's sugary beverage tax.
Mayor Kenney addressed the criticism around the tax.
"Your life doesn't depend on soda, so it's not like an elixir of life you need to drink or you die. So if you don't want to but it, don't buy it. People understand the importance of taking care of our children so that at some point in time the'll become tax paying purchasers or customers and the will have a job and they will have a fulfilled life."
The city expects the beverage tax to pump 12 million dollars into pre-K program this year.