Designing A Wind Turbine (Part 4)
Lesson 4 of 7
Objective: SWBAT determine the best idea for a wind turbine blade and test the design.
In Part 4 of this lesson series, I incorporate scientific inquiry as students design an investigation and then test their wind turbine designs. This stage is distinguishable from the others because the students are cutting out their designs and testing the amount of power each design generates. My strategies center around determining how to design an investigation, the testing of models, using a mathematical model to generate data, analyzing the data and finally presenting a conclusion.
The objective of this lesson is to have students use their investigation as a means to an end. The purpose of the investigation is not to do a science experiment. In STEM lessons the strategy is to use the investigation to defend a design.
Creating the Physical Model
In Wind Turbine Design Part 3, students worked in groups to determine the shape and dimensions of the wind turbine blade. In addition, they decided on the number of blades needed for their turbine design. In this section, they are using their design drawing and cutting out their designs.
I show students the materials to familiarize them and to build engagement. This hands-on scientific testing project is exciting to build and test.
I give the students the tools to cut out the wind turbine blades. I have Exacto knives, a pad for cutting, and rulers. Student groups work to cut out the blades. They glue a dowel rod onto the blade to attach it to a hub. Check out my Sample #1 and Sample#2
In the movie below, the student is explaining the science behind wind blade design. He has all the right words but watch and see how he doesn't quite understand the concept.
Designing an Investigation
The strategies are chosen to develop students’ knowledge and skills in designing investigations, testing models, using mathematical models to generate data, data analysis, and the crafting/presenting of a scientific conclusion.
I begin by showing all the equipment to the students and begin with the question, "How do you think we should test these designs?" Student groups discuss ideas and write the ideas on lap white boards.
Typically students answer, "Put the wind turbines together and see how fast they can go." My strategy is digging deeper in the engineering process. I ask, "How can we measure the speed?"
The students are stumped so I launch into a mini-lesson (Using Scientific Formulas). In that lesson students have practice using three data points, time, distance, and mass, to determine the kilowatts of energy their design can transfer.
The formulas include
- Distance/Time = Velocity
- Final Velocity – Initial Velocity/Time = Acceleration
- Mass x Acceleration = Force
- Force x Distance = Work
- Work /Time = Power
When I teach the lesson Using Scientific Formulas, I teach the ease of using mathematical modeling to calculate useful data.
Testing the Turbines
Armed with the Turbine Data Table and their designs, students are anxious to test the wind blades. When it comes to testing the models there are several common mistakes. Many groups leave the blade flat creating too much drag and the turbine does not move. Before I let the students test, I alert them to different challenges and solutions. I ask, "What if nothing happens and your design does not pick up any weight? What can you do?" We discuss Bernoulli's principle and determine that there are three changes we can make. We can change the angle of the blade to the wind, we can add or take out more blades, we can change the mass.
I allow students to practice with the materials before their official recordings. This gives them the opportunity to troubleshoot without consequence.
In this video, I explain the assignment and how to troubleshoot using the scientific principles.
Defending The Design
Using the data, students explain why this is an effective wind blade design. The conclusion demands scientific vocabulary. The purpose of the conclusion is to analyze the data to determine how well the turbine performed.
My strategy is Bullet Point Plan. I ask the students to use qualitative as well as quantitative date to defend their design. In their notebooks they write 5 bullet points. They must use the data they recorded in the testing of the designs. In addition, studetns write the scientific words they must use.
I explain that the bullet point plan and the defense they wrote before the testing of the design can be similar. They use what they know about Bernoulli's principle, back it up with data, to defend the design. In the power point, Wind Turbine Blade Designs, I've shown some samples of my Bullet Point Plan and the subsequent final draft of the design defense.
I call this writing piece a Technical report. I ask the students to add their Design Defense to the piece they wrote in Design a Wind Turbine Part 1. In Part 1 they wrote the introduction to the Technical Report when they explained why designing a wind turbine is an important design problem. They add their Design Defense as a second paragraph. If they have completed the 3D computer model, I ask the students to insert the model into the writing.
To evaluate I use my Turbine Rubric Checklist.