This is the teacher guide for this lesson. A student-focused guide to assist learners as they perform the activity is available.
Teacher Guide
Hot Shot Spinner
Experimenting with heat and pinwheels.
How does rising heat and blade tilt affect a pinwheel?
This resource was originally published in PhysicsQuest 2011: Spectra Heats Up!
How does rising heat and blade tilt affect a pinwheel?
- Tart pan
- Pencil (sharpened)
- 4 birthday candles
- Molding clay
- Lighter or matches
Students start by discussing the effects of air on spinning objects. During their experiment, they collect observations and data on the effects of hot air on a spinning object. They end the lesson by discussing other variables and forces on these same objects according to their observable data.
Safety
- Students will be working with open flame, making sure their workspace is clear.
Suggested STEP UP Everyday Actions to incorporate into activity
- When pairing students, try to have male/female partners and invite female students to share their ideas first
- As you put students into groups, consider having female or minority students take the leadership role.
- Take note of female participation. If they seem to be taking direction and following along, elevate their voice by asking them a question about their experiment.
- Total time45 - 60 Minutes
- Education levelGrades 5 - 9
- Content AreaThermodynamics
- Educational topicHeat, air
The physics behind the candle pinwheel is actually pretty simple. There are two components, heat rising and how this causes the pinwheel to turn. This neat yet simple physics is used for many things but one of my favorites is this “holiday pyramid” where carved wooden figures such as reindeer and angels are set on tiers and attached to a central axle.
There are candle holders throughout the structure and when they are lit, the rising heat causes a propeller on top to rotate and the reindeer to spin around. (Figure 1) When a gas such as air gets hot the particles in the gas start moving faster. Their average kinetic energy increases. Because the molecules now have the energy to move around more, they do and as they do they spread out and the gas becomes less dense. This lighter gas now rises up away from the heat source.
If a propeller is free to move and constructed correctly, the rising heat can now make it turn. The heat rises relatively straight up so to get the pinwheel to turn the blades need to be oriented in a way that causes the moving air to push them. Rising air will first strike the edge tilted down toward the ground. The air continues to rise and moves along the slope of the blade. As this happens the pressure on the side of the blade tilted toward the ground increases and the moving air pushes the blade. The pressure on the back side of the blade decreases which also helps the blade to move (Figure 2). This is very, very similar to an airplane wing. You can see that the direction of spinning is changed when the tilt of the blade is changed by roughly 180 degrees. In this experiment students will change the number of candles and therefore the amount of rising heat to see how the speed of the spinning is affected. They will also see how different blade orientations affect the direction in which the pinwheel spins.
Key terms
These are the key terms that students should know by the END of the two lessons. They do not need to be front loaded. In fact, studies show that presenting key terms to students before the lesson may not be as effective as having students observe and witness the phenomenon the key terms illustrate beforehand and learn the formalized words afterwards. For this reason, we recommend allowing students to grapple with the experiments without knowing these words and then exposing them to the formalized definitions afterwards in the context of what they learned.
However, if these words are helpful for students on an IEP, ELL students, or anyone else that may need more support, please use at your discretion.
- Pressure: How much push (or force) something gives per a particular area. You often here pressure with the unit “pounds per square inch.”
- Density: The amount of stuff (or mass) per volume. If there is more matter in the same volume the density is higher.
Before the experiment
- Ask & discuss
What can cause a windmill or pinwheel to turn?
- Snowball protocol
- Pair students up
- Give them a minute to think quietly
- Give students 2 minutes to discuss their thinking
- Have students record their answers or share out to the whole group
Setting Up
Sharpen the pencil and secure it point side up with the clay.
Put clay on the bottom of the four birthday candles and secure close to the pencil.
You will be making a pinwheel/windmill out of the tart pan. Make six, 2-inch radial cuts in the tart pan making sure to leave the middle intact to hold the “windmill” together.
Twist the blades 45 degrees counter-clockwise.
Carefully balance the tart pan windmill on top of the point of the pencil.
During the experiment
Collecting data
Make sure students are put into intentional groups. See above.
Students will complete the experiment using the Student Guide where we have outlined the experiment for students and along the way, they record results and answer questions.
Analyzing data
In the student guide, they will experiment with the effects of heat.
Continue to listen in on each group’s discussion, answer as few questions as possible. Even if a group is off a little, they will have a chance to work out these stuck points later.
Teacher tip
A great way to start any physics-related unit is with the STEP UP Careers in Physics lesson. This lesson covers careers one can do with a physics degree, particularly those that help solve societal problems. It helps students assess their personal values in relation to a career in physics, examine profiles of professionals with physics degrees, and envision themselves in a physics career.
Suggested STEP UP Everyday Actions to incorporate into the activity:
- When pairing students, try to have male/female partners and invite female students to share their ideas first.
- As you put students into groups, consider having females or students from underrepresented backgrounds take the leadership role.
- Take note of female participation. If they seem to be only receiving direction and following along, elevate their voice by asking them a question about their experiment.
Consider using whiteboards so students have time to work through their ideas and brainstorm before saying them out loud.
As students experiment, roam around the room to listen in on discussion and notice experiment techniques. If needed, stop the class and call over to a certain group that has hit on an important concept.
Consider using the RIP protocol (Research, Instruct, Plan) for lab group visits and conferring.
Consider culturally responsive tools and strategies and/or open-ended reflection questions to help push student thinking, evidence tracking, and connections to their lives.
Conclusion
Claim-pass protocol to have students share and refine their thinking.
- One person in each group writes a claim (can be provided by the teacher or not) at the top of a paper with the pencil in response to a recent observation of a phenomenon for the question: Why do you think the orientation of the blades affects the direction of the pinwheel?
- The student who wrote passes the paper and the pencil it to the left.
- The person with the paper writes one piece of evidence that supports the claim under the claim
- The paper and pencil are passed to the left.
After students have had a chance to discuss key ideas from the lesson and complete their student guides, you can now clarify and give concise definitions to the forces they experimented with.
- Real world connections -
- In the Intro, we said that we usually use wind to move a pinwheel. Using what we learned, describe how wind is created in much the same way that we turned the pinwheel today.
- Suggestions for drawing, illustrating, presenting content in creative ways
- Engineering and design challenges connected to the content
- How could we use the concepts you learned in this class to help combat climate change? Think big, be creative!
Wind Triange
In air navigation, the wind triangle is a graphical representation of the relationship between aircraft motion and wind. It is used extensively in dead reckoning navigation.
How does wind create all the ocean currents?
Ocean currents are mostly not created by wind. While wind can play a role, often minor, in shaping surface ocean currents, it is not the main or only factor. Furthermore, wind plays virtually no role at all when it comes to deep ocean currents.
- MS-PS4-3Integrate qualitative scientific and technical information to support the claim that digitized signals are a more reliable way to encode and transmit information than analog signals.
- MS-PS4-1Use mathematical representations to describe a simple model for waves that includes how the amplitude of a wave is related to the energy in a wave.
Credits
Written by Rebecca Thompson
Illustrations by Kerry G. Johnson
Activity illustrations by Nancy Bennett-Karasik
Updated in 2023 by Sierra Crandell, M.Ed. partially funded by Eucalyptus Foundation
Extension by Jenna Tempkin with Society of Physics Students (SPS)