Kindergarten Pool Party

My friend and I are planning a pool party in celebration of our 5 year old daughters going to kindergarten. We are having a hard time wording the invitations so that they include the fact that it is a pool party and that it is to celebrate that they are starting school this year. Most of the children that we are inviting are going to be starting school with them so it`s kind of a celebration for all of them. HELP???