T-GEM, PhET and Friction

Understanding the effects of friction on the motion of objects can be a difficult concept for some students to understand. To explore the topic further, I designed a blended lesson using the T-GEM model and a PhET simulation, along with two others. The de Jong and van Joolingen (1998) review of simulation use in discovery learning contexts cited the importance of structuring and supporting students’ work in ways to prevent difficulties (Stephens, 2014). The teacher will lead some aspects of the lesson but students will be active participants throughout. Small groups will record observations and responses on this collaborative document which will help guide and structure the experience.



Prior knowledge accounts for the largest amount of variance when predicting the likelihood of success with learning new material (Srinivasan, 2006). Therefore, it is essential to activate relevant prior knowledge. Students will discuss and analyze scenarios where friction is the cause of their observations. Two common ones at my school would be tobogganing on the hill and hitting a patch of grass or participating in Halloween gym and having to scooter over a long stretch of carpet. Students will also play a game emulator of Mario Kart (http://www.nintendoemulator.com/snes/781) and drive over different surfaces and use different characters to observe the impact that their characteristics have on the motion of the vehicles. Students will explore a simple BBC simulation (http://www.bbc.co.uk/schools/scienceclips/ages/8_9/friction.shtml) in which they can test the effects of different surfaces on the motion of a vehicle using the same applied force. Students will record observations on the recording sheet and generate ideas regarding the relationship between friction and motion.

Students will then engage with a more detailed PhET simulation at https://phet.colorado.edu/en/simulation/forces-and-motion-basics. They will freely engage with the simulation but also use information on the recording sheet to test specific scenarios to observe and compare the interaction of multiple variables in more detail.


Students will engage in a whole class lesson using the simulation. The teacher will highlight crucial concepts, spend time addressing conceptual difficulties, focus on key visual features of the simulation (frictional force), and promote students using key visual feature in their thinking (Stephens, 2015). Students will evaluate their generated ideas relative to their whole group experience.


Students will go back and use the simulations again. They will reread answers on the recording sheet as well. They will have the opportunity to revise and update their groups initial responses to reflect a new more comprehensive understanding.

Using a variety of objects, surfaces, and spring scales, students will create a real-life scenario that demonstrates the effect of friction on the movement of objects based on the simulations they used.


Srinivasan, S., Perez, L. C., Palmer, R., Brooks, D., Wilson, K., & Fowler, D. (2006). Reality versus simulation. Journal of Science Education and Technology. 15(2), 137-141.

Stephens, A. L. (08/2015). Computers and education: Use of physics simulations in whole class and small group settings: Comparative case studies Pergamon Press. doi:10.1016/j.compedu.2015.02.014


  1. Hello Derek,

    I enjoyed reading your post. Friction is a rough one, for sure :). I find that most students know its there and have some sense of proportionality, but they don’t understand the root mechanisms of the complex system. Jacobsen and Wilensky (2006) conclude that studying complex systems like at an agent-to-aggregate level is really important and should occur more in K-12 education.

    Does you find that the use of PHeT helps them understand the difference between static and kinetic friction? My students have a hard time with that.

    Perhaps using a Vernier force probe to visualize the “stick and slip” phenomena could bridge that gap. I’ve not yet tried it myself.


  2. I haven’t been able to use the PhET simulation with students yet but plan to. I think it will be particularly helpful making connections to math. I also like how you can alter what information is visible. I have typically studied friction in relation to a design project but I think the simulation and T-GEM model will help study it in more depth.

  3. Hi Derek,
    I liked how you created a collaborative document where the students can record their observations. Under your modify step, I wonder what the students will appreciate / learn more from: the PhET model or recreating their own real-life scenarios?

  4. That is a great question. I would hope that each experince would help support and deepen learning in the other. I think the visual mathmatical representations of the different forces would help students make connections that might be harder to conceptualize in a real-lile experience like the one described.

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