This lab is a guided inquiry lab where students learn how to take experimental data and verify an existing equation.
The only materials needed are a piece of sting, a mass (anything), a place to hang a pendulum from and a stopwatch (I use cell phones).
This lab take about 1.5 hours and requires a lot of critical thinking on the students part.
The lab forces the student to examine the equation, figure out which variables they can measure (independent and dependent) and then use algebra to rearrange the equation. The students then graph the equation and can do an error analysis - comparing their result to the accepted value of gravity.
This lab is not endorsed or affiliated with AP in anway - it can also be used a regular high school physics lab.