## Reflection: Problem-based Approaches Designing a Wind Turbine (Part 3) - Section 3: Explaining the Designs

Constraint is defined as a limitation or a restriction. In solving design problems common constraints include time, cost, and materials. Students may consider time as a constraint if their design is complex and difficult to build. Some teachers add a cost constraint by "charging" more for the blade material and the number of blades the students want to build. The materials are a constraint because as teachers, we are limited to the materials at hand. In their research students have reported the use of carbon fibers. Without the budget for such expensive materials, we are all constrained by balsa wood and plastic although I have had students a use tag board.

In my student led classroom I ask the students to determine the criteria for success. They have conducted the research and through my assessments I am confident they know what they need to do. Typically students will use the following criteria:

1. Curved blade (Bernoulli's Principle) Students will say that it has to work. I ask,"Define what it needs to work." I have also had students use the word "functional". I ask for the science behind the functionality.

2. Blade complexity: time to create a prototype to test.

3. Blade size: this is also a constraint because we are constrained by the material.

The importance of the criteria is two-fold. I can increase rigor by adding criteria. I might say, "It must be 10" long and 3" in wide. Student must take additional measuring steps and it makes developing different designs more challenging.

The criteria is also important for the grading rubric. In my student led class, I ask the students, "How should I grade this activity?" We develop the rubric together. This has powerful implications because the students develop the proficient criteria under my supervision.

Criteria vs. Constraint
Problem-based Approaches: Criteria vs. Constraint

# Designing a Wind Turbine (Part 3)

Unit 7: Designing for the Future: Wind Turbine Design
Lesson 3 of 7

## Big Idea: The fun starts here. Students are armed with lots of cool scientific information and now they can start the designs! They explain how their designs are great solutions to the problem.

Print Lesson
Standards:
Subject(s):
78 minutes

### Sydney Schuler

##### Similar Lessons

###### Wind Turbine Blade Design Part 1: Define the Problem & Research Solutions
8th Grade Science » Engineering: Wind Turbines
Big Idea: In this first lesson of a unit on wind turbine blade design, students are presented with the problem of designing wind turbine blades that will produce the optimal amount of electricity.
Favorites(6)
Resources(16)
Brookline, MA
Environment: Urban

###### Using Rube Goldberg Simulation to Demonstrate Understanding of Energy Transformations
Big Idea: Learning science should be fun and meaningful and this lesson provides students with that opportunity.
Favorites(12)
Resources(12)
East Walpole, MA
Environment: Suburban

###### Design Your Own Simple Machine
6th Grade Science » Simple Machines
Big Idea: Engineering practices come into play for this hands-on design lesson where students create their very own example of a simple machine!
Favorites(15)
Resources(17)
Brooklyn, NY
Environment: Urban