Laws of Motion Lesson #1: Newton's 3rd Law
I love a good hands-on activity, and some of my favorites are for teaching Newton’s laws of motion!
This is the first of a 3 part series of physics lessons for junior high students, each lesson on one of Newton’s three laws. Check back for the next 2 lessons, coming soon! (I will link them here after I post them!)
In this post, I am sharing one of my favorite hands-on activities for teaching Newton’s third law of motion. For every action there is an equal and opposite reaction, and what better way to demonstrate than with water balloons??
This lesson is similar to an egg drop, but with real-world application and less mess!
Lesson Description
Summary: Students learn about the Mars Lander. Each group will then design, build, and test a device the absorbs the forces of impact to protect their water balloon “astronaut.”
Learning Objective: Students will design, build, and test a device that absorbs the forces of impact.
Time Required: Flexible, but I usually use 2 or 3 60-minute class periods.
Materials Needed:
- Mars Lander Instructions Slides
- Water Balloons – I like these cheap balloons because they are easier to pop, which makes the challenge harder for kids. BUT also, I recently got these re-useable water balloons for my toddler and LOVE them for easy filling and clean up! You would just need to use bigger cups if you use the re-useable ones.
- Straws – Restaurant style drinking straws without the bend. I usually pick up a box from Costco, but this 500 pack of straws on Amazon look even better because they aren’t individually wrapped. Less kids blowing wrappers at their friends is definitely better for your sanity.
- Plastic Cups – again, cheaper is better here. It’s fun when the plastic cracks and pops the balloons. I use 250 ml size (about 7 ounces)
- Rubber Bands
- 3×5 Index Cards
Introductory Activity
Begin by sharing the video “7 minutes of Terror: The Challenges of Getting to Mars.” It’s an awesome video narrated by the scientists who work on the Mars Lander, discussing how they get it to land on Mars safely.
I use this video to introduce the “problem” to students and help them see the real world application behind the activity.
If you skip this step, it’s still a fun activity, but adding the connection creates a more professional atmosphere for students.
Plus, the video is just really really cool!
Lesson Resources
These are the Slides that I use to guide my class through the activity (see video preview).
You can make a free copy of the slides by clicking here: Mars Lander Slides.
Please feel free to edit them to your needs and share with your team teachers. I just ask that you respect the copyright. Thank you!
Testing Process
After students have completed their designs, it’s time to test!
I set up a “drop zone” in my classroom by taping a few yard sticks to the wall and marking the height every foot from 4 feet up to the ceiling.
I used to have the kids drop the balloons onto a tarp, but it cushions the balloons too much. Instead, I just keep a mop and towels handy to wipe up between tests.
Each group takes turns dropping their lander from each height. They are not allowed to repair the lander if it is damaged in any drop. When the balloon pops, they are out of the challenge (but I give them a new balloon for one final BIG drop, shown in the video below).
At the end of the testing, head outside or to the gym for an extra-tall drop! At my school, we drop them off the bleachers down onto the basketball court, which is about a 15 foot drop. The kids absolutely love this extra drop so I highly recommend it if you are able!
For a final assessment, students draw a force diagram for their Mars Lander in their notebooks. Students label the diagram with force arrows that show the action and reaction forces.
Finally, I have them write a brief conclusion describing the laws of motion that they observed in this activity.
How was it?
I would LOVE to hear your feedback for this lesson! How did it go? What other fun activities are you using to teach laws of motion? Please share in the comments!
For more hands-on science activities, check out my science lesson library here.
Love this fun lesson! I’m planning to do this with my 8th grade class next week.
Point of clarification: In the materials needed you mention straws without the bend, but your photo shows bendy straws being used. Was that all you had when you made it? Or did you actually mean to type straws with the bend? I want to make sure as I’m making a list to get these items. ☺️
Also, the Amazon link for plastic cups goes to the 500 pack of straws rather than the cups. Thought you might like to know. The other link work great!
Again, thank you for such an awesome example! Can’t wait to see how it goes with my class!
I’m so glad you like the lesson and I hope you it goes well for your 8th graders! I never used straws with a bend in them but the kids would bend them, so that is likely what you see in the picture. I think you could use either and it would work well. Thank you for letting me know about the error with the link! That should be fixed now. Happy teaching!😃
Love this fun lesson! I’m planning to do this with my 8th grade class next week.
Point of clarification: In the materials needed you mention straws without the bend, but your photo shows bendy straws being used. Was that all you had when you made it? Or did you actually mean to type straws with the bend? I want to make sure as I’m making a list to get these items. ☺️
Also, the Amazon link for plastic cups goes to the 500 pack of straws rather than the cups. Thought you might like to know. The other link work great!
Again, thank you for such an awesome example! Can’t wait to see how it goes with my class!