# Exploring Bernoulli's Principle

## Objective

SWBAT explain Bernoulli's Principle can be used to design a air foil/wind blade for a wind turbine.

#### Big Idea

When designing Wind Turbine blades, students determine how Bernoulli's Principle impacts the design of wind blades.

## Engage

15 minutes

I begin the lesson with a compare/contrast of air foils for airplanes and turbine blades of wind turbines. I am a private pilot. I made a movie for my students to help them understand Bernoulli’s principle. See my reflection about home movies.

I ask, “Is the science different between a wind turbine blade and an airplane wing?”

I use a Debate strategy. The students who think the science is the same, go to one side of the room. The others go to the other side of the room. I give them time to work together. Their task is to convince the other team members to join their side using my movie as a reference. If asked, I show the movie again. My intention is for students to think about Bernoulli's principle and communicate the components of speed, pressure, lift, and curve. I write the words for them on the board to help them use the important vocabulary.

## Explore

10 minutes

My next strategy is to demonstrate science content with an emotional demonstration.  To demonstrate Bernoulli’s principle, I have a leaf blower and a roll of toilet paper on a dowel rod.  I give students a 4' x 7 " piece of paper. I ask if anyone knows from their research or from background information what Bernoulli's Principle is. After the informal discussion, I explain how I am going to levitate the paper by blowing over it. I welcome the students to do the demonstration also. After the demonstration students work with groups of four in a strategy called Write It-Draw It. Two students are assigned to explaining the demonstration in writing, one explains in a drawing. I formatively assess as students work and scaffold understandings.

When all the groups have finished Write It-Draw It, I pull out my leaf blower and toilet paper. I ask for volunteers. Two students hold the dowel rod and one student directs the force of the leaf blower at the paper, it rises up, and the roll of paper takes off. Think Blue Man Group.

I do the demonstration once and ask students to observe the toilet paper ends. They explain that the toilet paper went up. I ask, “Why?” Student groups go back to their Write It-Draw It and explain why the paper lifted using science vocabulary.  I tell them, “The way a wind turbine blade works will help you understand what happened to the toilet paper.”

I do the demonstration again, this time the student does not point the leaf blower at a spot and it will not work. My strategy is called Do The Opposite. I'm trying to challenge the students to think about why the leaf blower did not work. Students explain how the air low was not directed over the top of the curve.

Finally, we conduct the demonstration again so that it works. My next strategy is a Two-Minute Review. Students work in pairs and tell one another why the demonstration worked.

In my Bernoulli's Principle video, you will see my introduction to students. I ask if anyone has heard of Bernoulli's Principle and a student attempts to explain his understanding of the concept.

I almost didn't include his explanation, but I wanted to show you how close a student can be. My gut is that he has some understanding, but it is obvious he needs the vocabulary to explain it.

In addition I filmed my two demonstrations. There were other classes in which the student with the leaf blower does not direct the wind stream in the correct spot and it doesn't not work. This still works, because you can ask, "Why didn't it work?"

## Explain

10 minutes

I explain that the same force that lifted the toilet paper also makes wind turbines work. We watch Energy 101 from the Department of Energy.

The first time through, I stop the movie looking for words that someone might not understand. I add these words to my Word Wall. The students are completing research questions as part of my Wind Turbine Design Part 2 Lesson. I remind students of the research questions and tell them they can use the movie as a reference for any questions. The Word Wall words will be a visual reference for the students as they complete the writing portions of the Wind Turbine Design Lessons.

I show the movie again, this time stopping the movie to help students understand science concepts. My intention is to give students time to write information as well as giving the students think time.

## Evaluate

10 minutes

The purpose of this section is to use Bernoulli's Principle to defend a design. My next strategy is to use a conceptual model to help promote an understanding of science content. In Mrs. Schuler's Flight movie there is an image of Bernoulli's principle. I project the image and students copy the model into their engineering notebooks.

Students need not memorize the content. They need an easy reference to help them defend a design solution.  To evaluate, I ask the students to draw a design of an air foil and label it to explain how Bernoulli’s principle will effect the performance of the design. They must explain the shape they drew and why. In addition, we are using science vocabulary in writing a defense.