This is a great two part lab that can be done over 3 or 4 days (Depending on your classes etc). The first part of this lab is a directed activity on acceleration with small toy cars (I use hot wheels). Your students will collect data, graph it, calculate and answer analysis questions. The second part requires them to create their own lab using bouncy balls and calculating acceleration. The second part of the lab is a great way for the students to show their curiosity and creativity within the science classroom. I have done this for a few years now, and each year my students tell me it was one of their favorites.
If your students need a little more practice with acceleration, check out my practice worksheet: http://www.teacherspayteachers.com/Product/Acceleration-Practice-972387
(Science, middle school, physics, lab, activity, acceleration, cars, creative)