Teacher Guide

# Drinking Bird Races

## An exploration of using metal to melt chocolate

How do different metals conduct heat?

This resource was originally published in PhysicsQuest 2011: Spectra Heats Up!

This is the teacher guide for this lesson. A student-focused guide to assist learners as they perform the activity is available.

View the student guide: Drinking Bird Races

How do different metals conduct heat?

• 2x Drinking Birds
• Large plastic bag
• Cup of water
• Stopwatch

Students start by discussing what they already know about evaporation. If students are stuck, give them an example and ask them to describe what they think is happening. When they experiment with a drinking bird, they will collect data with different variables. In the concluding discussion they will work together to refine their thinking about the differences between how the drinking bird was affected by different liquids.

• Total time
45 - 60 Minutes
• Education level
• Content Area
thermodynamics, conduction, convection
• Educational topic
thermodynamics, conduction, convection

The liquid in the bottom begins to move up the bird’s neck to fill the space left when the gas condensed. As the liquid moves up, it makes the head of the bird heavier and causes it to tip forward. When that happens, the tube that extends into the bird’s bottom half ends up above the level of the liquid and a gas bubble can now move up the neck. This bubble of vapor pushes the liquid back down the neck which causes the bird to tip back. Then the whole thing starts over again. Notice that the bird rocks back and forth a bit when it pops back up. This is not the periodic motion we are talking about. In this experiment a period of drinking is from when the bird is horizontal and back to that point. The felt in the head is important because it will absorb the water and allow it to evaporate slowly. Most times you will see a bird dipping into a cup of water with every tip. The bird will go for a long time without needing a glass of water, but once all of the water evaporates from the head the bird will stop unless it can get more. The beak of the bird soaks up water every time it dips into the glass and this allows the bird to continue its drinking. As the bird dips and comes back up it is undergoing periodic motion. It continues to return to where it started. But what can affect the period of the bird’s motion? Really the only thing we as experimenters have control over is the process of evaporation. In the first experiment the students will look at how the period changes when alcohol is used instead of water. Because the alcohol evaporates more quickly, the whole drinking process will speed up and the bird will have a shorter period. If you have time, you could also try using water of different temperatures. In the second experiment the students will place a bag over the bird and watch it stop. This happens because the air inside the bag becomes saturated and no more alcohol can evaporate from the bird's head so there is nothing left to drive the motion. When the bag is removed the bird again starts to drink. If you have time, soak one bird’s head in water and one in alcohol and let them go. In addition to seeing which one drinks more quickly, let the birds go until they stop moving. Don’t add any water or alcohol to the birds’ heads. The bird covered in alcohol moves more quickly because the alcohol evaporates more quickly but this also means the bird will stop moving sooner as it loses its “fuel” at a faster rate. The bird dunked in water may be slow but he will go forever.

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.

• Periodic Motion: When the motion of an object is periodic it follows a set path repeatedly. It always ends up back where it started. The motion of the planets or pedaling on a bicycle are examples of periodic motion.
• Period: The period is the amount of time it takes for an object undergoing periodic motion to return to its starting place.
• Evaporation: Evaporation is a process that cools things off. Molecules of a liquid that have the highest temperature (most kinetic energy) fly off of a surface leaving only the cooler molecules behind.
• Evaporative Cooling: As liquid evaporates off of something such as skin, the molecules that leave take a lot of energy with them leaving the skin cooler than it started. This is why sweat is an effective way of cooling the body down.
• Condensation: Changing from a gas to a liquid.
Before the experiment
• Watch this video of the drinking bird apparatus.

• Ask & Discuss: What does ‘evaporation’ mean?

1. Pair students up
2. Give them a minute to think quietly
3. Give students 2 minutes to discuss their thinking
4. Have students record their answers or share out to the whole group
Setting up
• Take both birds out of their boxes and set them side by side. Label them “alcohol” and “water.” Or, if you want to, feel free to name them. Alfred and Walter have a nice ring to them.

• Slide the bird in the metal cuff till it’s in the middle of the bird. This will allow the bird to balance correctly.

• Open the bag and make sure it can fit over the drinking bird without touching it or getting in the way of its “drinking.”

• Place a cup of room temperature water in front of the “water” bird.

During the experiment
Collecting data
• In the student guide, they will adjust their experiment and record observations.

• 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.

Analyzing data
• In the student guide, they will adjust their experiment and record observations.

• 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
• Write-Pass protocol to have students share and refine their thinking.

• Divide students into groups of four. (Different from their experimental groups)
• The teacher posts a question that students must answer with an explanation. Thinking about the differences between alcohol and water as well as what happens when you place the bag over the bird’s head, what do you think is causing the bird to “drink?”
• Students each write their own ideas on a loose piece of paper.
• Then the papers are all passed to the left.
• Each student silently reads the student’s response (and any of the other students’ comments, on iterating rounds of this process).
• Each student writes suggestions directly onto the original copy to help make their peers’ ideas sharper and clearer.
• Repeat the pass-read-edit until each student gets to read and comment on each others’ ideas.
• The original author of each statement reads their peers comments and writes a refined, final statement at the bottom of the paper to turn in.
• 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 -
• Something like get list of other liquids that evaporate compared to these and rank which would go faster/slower?
• Suggestions for drawing, illustrating, presenting content in creative ways
• Engineering and design challenges connected to the content
• MS-PS4-3
Integrate 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-PS4-1
Use 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)