Using PhET simulations in high school – Open-ended Pendulum Labs

Compiled by Sam McKagan, based on material from Trish Loeblein
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This material is replicated on a number of sites as part of the SERC Pedagogic Service Project


Pendulum Lab

These labs provide examples of using very open-ended questions to guide students in exploring a simulation and designing their own experiments. These labs can lead to a high level of quantitative thinking about data analysis.

Learning Goals

Pendulum Lab 1 Learning Goals: Students will be able to:
  • Design experiments to describe how variables (length, mass, angle and gravity field) affect the motion of a pendulum
  • Use a photogate timer to determine quantitatively how the period of a pendulum depends on the variables
Pendulum Lab 2 Learning Goals: Students will be able to:
  • Design an experiment to determine the gravitational acceleration for an unknown planet

Context for Use

These labs were designed to be used in a high school physics class, but are sufficiently advanced that they could also be used in an introductory undergraduate physics class. This activity could be done in class, or assigned as homework. However, if students are not used to open-ended questions it is probably better to do it in class so that you can help them if they get stuck. The activities require students to work with the simulation, so students should have access to computers at home if it is assigned as homework, or in class if it is done there. Students can work in groups of 2-4, and there should be a computer for each group.

The first lab assumes that students have already done the curve fit activity (linked below), and that they have access to and know how to use a graphing program such as Excel.

The second lab assumes that students know how to search (their textbook or the internet) for information that is not given, and that they know how to do some kind of error analysis.

Description and Teaching Materials

There are two pendulum labs, which could be done in sequence, or either one could be done as a stand-alone lab.

First pendulum lab:

Second pendulum lab:

The first pendulum lab builds on the following curve fit activity:

The pendulum labs use the Pendulum Lab simulation:

The curve fit activity uses the Curve Fitting simulation:

Teaching Notes and Tips

If students are not used to open-ended design labs that don't tell them exactly what to do, they may be uncomfortable at first. It is best to use this kind of lab consistently throughout a course to allow them time to get used to it, rather than just trying it once. Emphasize that what you want them to learn from this lab is the process of designing a lab, not just getting the right answer, and grade accordingly.


These labs should be graded based on how well students are able to design an experiment and discuss the various factors that affect their results, not just on whether they get the right answer.

References and Resources

For similar activities for high school physics, search for "Loeblein" on the PhET Activities Database:

For more information on how to teach design labs effectively, see the last chapter of:

Paul Gresser, "A Study of Social Interaction and Teamwork in a Reformed Physics Laboratories," PhD thesis, University of Maryland, 2006.