THE PRESSURE'S OFF II- FLIGHT
Grades 3-6

In this lesson and its extension the students will have an opportunity to learn what allows air planes to fly, why birds can fly, and why people can't. This lesson contains several hands-on activities that teach Bernoulli's Principle and allows the students to implement the understanding of it. The group will construct a giant hot air balloon that can be launched using only a hair dryer.

Scientific Eye #8: Lighter than Air

Students will be able to:

• define and demonstrate Bernoulli's Principle
• measure to the nearest centimeter
• give examples of Bernoulli's Principle at work
• describe what happens when air is heated

Bernoulli's Principle I

• 1 funnel top of a two liter bottle per group of three
• 1 small balloon per group of three
• 1 hair dryer per group of three

Bernoulli's Principle II

• 5 cm X 20 cm piece of paper
• measuring device
• scissors
• Hot Air Balloon
• 8 55 gallon commercial garbage bags per group
• cellophane tape per group of four
• measuring device per group of four
• scissors per group of four
• hair dryer per group of four

Ask the children "Have ever taken a shower curtain stick to you when the water is running in the shower?" "Does it look like someone is outside the shower pushing the curtain in?"

NOTE TO TEACHER: The expected response it that the students would notice the shower curtain moving inwards as though there was someone on the outside pushing it in.

After the students have given their responses, ask them what actually caused the curtain to move inwards. At this time don't give any explanation as to what was happening to cause the curtain to move inwards.

The title of this video is "Lighter than Air" and we are going to see if there is anything that is truly light than air. Group one, I want you to see if you can figure out what is causing the shower curtain to go inwards when the shower is running. Group two, I want you to see if you can identify three different heat sources used to launch hot air balloons. Group three, please see if you can identify the problem with making a small hot air balloon. And group four, identify the different types of hot air balloons that were shown.

BEGIN the video Scientific Eye #8 where the boy is blowing up the balloon and PAUSE after "Guess what is holding up this unidentified object." Allow the children to guess. RESUME the video and pause after "And this beach ball?" Allow the children to guess again. RESUME the video and PAUSE after "Cut off the air stream and the ball drops." Give the groups the funnel made from the two liter bottle, the balloon and a hair dryer. Instruct the students to inflate the balloon and tie it off so no air can escape. Put the balloon inside the funnel and direct the hair dryer so it will blow into the mouth of the two liter bottle. Turn the hair dryer on and observe what happens. Hold the balloon inside the funnel as the large end is pointing toward the floor. Turn the hair dryer on and observe what happens. Discuss the results and why they happened.

NOTE TO TEACHERS: This is Bernoulli's Principle in action. Air moves faster around the balloon causing the air pressure to be less than the pressure below the balloon allowing the balloon to not be affected by gravity.

FAST FORWARD without sound (the rationale for no sound is that what is being said does not address the curved shape of the objects) to the eagle in flight. PAUSE at that point and ask the students to observe the shape of the bird's wings. RESUME the video and PAUSE as the glider is taking off. Ask the students to observe the shape of the gladder wings. Ask what the eagle and glider have in common.

NOTE TO TEACHER: Both the bird's wings and the gladder wings are curved on top and straight across the bottom.

Give each child a piece of paper and ask them to measure and cut a piece that is five cm by twenty cm. Instruct the students to lay the paper over their index finger. Tell them that they will place the paper under their lower lip and blow. Before they do this, ask them to predict what will happen with the paper when they blow air over it. After they have made their prediction, have them do the activity and observe what does happen.

NOTE TO TEACHER: The paper will come up and flap in the wind. The reason for this is again, Bernoulli's Principle. Air travels faster over a curved surface, allowing the air pressure to be greater on the bottom of the paper that it is on the top so the paper is pushed up. This is what creates lift allowing airplanes to fly.

FAST FORWARD to where the clouds are forming in the sky. PAUSE after the question "How could we use hot air to lift something up?" Allow students to answer. RESUME the video and PAUSE after the question "Will the hot air from a hair dryer be enough to lift this trash bag?" Allow the students to make a prediction. RESUME the video and pause after the question "What will happen when the bin liner is filled with hot air?" Allow the students to make a prediction. RESUME the video and PAUSE after the question "What will happen when you blow out the flame and the balloon cools down?" Allow the students to make a prediction. RESUME the video and PAUSE after the flame was blown out. Discuss all of the students' predictions. RESUME the video and PAUSE after each of the following questions allowing the students to make predictions: "Do you think these liners are a sensible material to use?" "Does the color of the material make any difference?" "What sort of material would you choose to use to make a big balloon?" How would you make enough hot air to fill it?" RESUME the video after each question to allow the students to make observations about their predictions. STOP after "But that project had to be put off to another day." Discuss with the group all of their observations. Go back to the focus for viewing and ask each group to tell the answer to their question. Discuss any of the questions the students might have.

Using the information you have just gained, we are going to design hot air balloons made from trash bags. I will be handing out the directions for this activity. Please read through the activity before you begin any part of it. Please assign jobs within your group so that all are actively involved. (See Appendix A.)

NOTE TO TEACHER: You will probably have to lead the group through this activity one step at a time. When all of the groups have completed the hot air balloon, it is launch time. Each group will need a hair dryer and possibly an extension cord. If you have a gym or a room with high ceilings you might choose to do this inside. This can also be done outside, but you would probably want to have a tether rope on the balloon to keep it from going too high.

Invite a hot air balloonist to come to you school for a demonstration if possible and a talk about his/her experiences while using the hot air balloon.

Invite an airplane pilot to come to you class to talk about the importance of Bernoulli's Principle in flying airplanes.

Language Arts:
Have each student write a lab report on the activity they did in the post-viewing activity.

Do research on Bernoulli's Principle

Social Studies/ Arts:
Write a report on the use of hot air balloons in the history of the world.

Science: Make the hot air balloons using a different colored garbage bag.

Math:
Put a tether on the hot air balloon. Using the tether, measure how high the balloon goes and then do the same process to see if color does make a difference as to how high the balloons will go.