I do this lab with both my 9th grade General Science classes (all levels) and my 10th-12th grade Physics classes (all levels). Probably also suitable for advanced middle school classes.
This is a lab that we do to bridge between conservation of energy and conservation of momentum as well as to help students develop their "ratio thinking". Students drop several different kinds of balls from various heights and measure the height to which the ball bounces. They then calculate the ratio of the bounce height to the original height and compare numbers for both different heights (should be the same) and different balls (usually different).
One of the teachers at my school also uses this as his "introduction to doing labs" activity because it contains all the important elements of our labs but has minimal setup and straightforward measurement for students to practice.
You will need several different types of balls (tennis, golf, Ping-Pong, lacrosse, etc), meter sticks, and tape to affix the meter sticks to the wall.
Setup / Intro: 5 min
Data collection: ~15 min (depends on class size & level)
Calculation & Group chat / analysis: ~15 min
Debrief -> discussion of "collisions": 10 min