Historically, Galileo's discovery of the pendulum motion played an imperative role in undermining the Aristotelian physics. A way of finding the pendulum motion can be integrated with abilities to do inquiry and understandings about inquiry as well as nature of science.
Students are asked to generate a pendulum and time how long it takes their pendulum to go through ten cycles. Then, they are asked to find any variables that influence the time for their pendulum motion.
Contrary to the real pendulum motion, students believe that the mass of a bob hanging on the string affects the pendulum motion, which may influence their investigations. The NOS discussion can deal with how scientists' prior knowledge (e.g., background theories) affects their investigations. In terms of scientific inquiry, the pendulum motion is a common activity to teach the concept of controlling variables through a discussion about why only one variable should be manipulated (e.g., length, mass, or height from it is dropped).
Different kinds of bobs (e.g., different types of balls, nuts, washers, etc.) and strings, measure sticks, scales, and stop watches.