Students love slumber parties or sleepovers and they will love planning their ultimate party. If you're looking for a fun and engaging project based learning unit, this pbl unit includes math, technology, writing, and 21st Century Skills. First, students write a persuasive letter telling why they should have the party. Activities include: inviting 10 friends and deciding on entertainment and the food you want to serve. They are required to stay within their budget of $200. WHY TEACHERS LOVE PBL.