This article (which you can get for free) shows the physics and what you will need to do water balloon launcher to teach projectile motion. It includes the air drag factor, since this is done not in the world of Angry Birds, but in real life.
Abstract: A simple, collapsible design for a large water balloon slingshot launcher features a fully adjustable initial velocity vector and a balanced launch platform. The design facilitates quantitative explorations of the dependence of the balloon range and time of flight on the initial speed, launch angle, and projectile mass, in an environment where quadratic air drag is important. Presented are theory and experiments that characterize this drag, and theory and experiments that characterize the nonlinear elastic energy and hysteresis of the latex tubing used in the slingshot. The experiments can be carried out with inexpensive and readily available tools and materials. The launcher provides an engaging way to teach projectile motion and elastic energy to students of a wide variety of ages.
There ya go!
What I like about this one than the common projectile motion demo that occurs in many high school is that there is quite a careful thought being given to the physics. One can do this as simple as one wants to, or ramp up the complexities by including factors that are not normally considered in such situation.