# Engineering Design Project: Parachutes (Day 2)

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## Objective

SWBAT follow the steps of the engineering design process to create the best parachute to slow down the affects of the force of gravity.

#### Big Idea

Students work in teams to test and build a parachute that will take the longest to reach the ground.

## Rationale and Preparation

The Why Behind Teaching This:

This unit covers standard 5-PS2-1: Support an argument that the gravitational force exerted by Earth on objects is directed down.  During the unit, students will investigate a variety of objects to see that the force of gravity is constant on Earth and pulls things down towards its center.  We will also be investigating a variety of ways to overcome gravity.

Several of the lessons in this unit are engineering design projects requiring students to follow the steps of the engineering design process to construct a project.  These projects address standard 3-5-ETS1-1: Define a simple design problem reflecting a need or a want that includes specified criteria for success and constraints on materials, time, or cost. It also addresses engineering standard 3-5-ETS1-2: Generate and compare multiple possible solutions to a problem based on how well each is likely to meet the criteria and constraints of the problem.  There are also several experiments in the unit which address standard 3-5-ETS1-3: Plan and carry out fair tests in which variables are controlled and failure points are considered to identify aspects of a model or prototype that can be improved.

This specific lesson addresses the science standard 5-PS2-1 because it provides evidence that the the force of gravity is directed down towards Earth by pulling the parachutes down.  The activity in this lesson is an engineering activity so it also covers the two engineering standards, 3-5-ETS1-1 and 3-5-ETS1-2.

Lesson Goal:

The goal of this lesson is for students to follow the steps of the engineering design process to plan, build and test parachutes and determine which characteristics would make the best parachute.

Success Criteria:

Students will demonstrate success on this goal by creating a parachute that opposes the force of gravity, slowing down the affects, thus making their parachute fall to the ground the slowest during the final trial.

Preparing for Lesson:

Building:

• Scissors
• several large, medium, and small circles and squares cut from a white sheet
• several large, medium, and small circles and squares cut from white paper
• several large, medium, and small circles and squares cut from white trash bags
• 1 clip of the same size for each group to use for their load
• string or yarn
• measuring tape for each group

*By precutting the circles and squares, I am ensuring that all canopies are equal in size and eliminating the time it takes to trace and cut them out for students.

Testing:

Window on the second floor for testing parachutes

## Building

45 minutes

Building Continued from Day One

Groups completed the planning sheet on day one of this activity.  Some groups began building their parachutes then, while others are just now beginning.  There are several different variables that groups will be testing to determine what makes the best parachute.  The building and testing will take at least 45 minutes.  There is a material center that is located on a table in the classroom.  This table holds all of the materials for the various tests.  Groups must return materials from one test before getting materials for another test.  This helps keep the classroom organized.

I circulate around to help groups properly transition from one test to another. One thing that I noticed students struggling with was remembering to keep one variable constant once they test it and find out which is best.  For example, once they test the length of the strings, if they find that the 20cm length is best, then all parachutes moving forward should have 20cm length strings.  They will then build their next three parachutes, all with 20cm length strings, but change another variable such as canopy shape.  So they will have a small circle with 20cm strings, a medium circle with 20cm length strings, and a large circle with 20cm length strings. Once they figure out which size is best, let's say the medium, then they will make all parachutes moving forward with medium canopies that have 20cm length strings, and change another variable such as shape and test a medium square and medium circle.

In the video of a group assembling their parachutes to test shape, you can see that this group has a medium square cut out of paper and a medium circle cut out of paper.  They are attaching the strings which should all be the same length.  Once they test these two parachutes they will know if which shape is the best and will use that same shape moving forward.

In the video of group tracing a cloth circle for their parachute, you can see that this group has the large bed sheet which is used for the cloth parachutes.  They are tracing the bowl that I set out to be used for the medium circle.  It is important to have something to trace for each shape and size so that it stays consistent for all groups.

Testing Each Variable

Groups will have three parachutes to test for all variable tests, except the shape (they only test circle versus square).  There are three students in each group which means two students stay upstairs in the room to drop the parachutes, while the third group member goes downstairs and stands outside the window.  To test each variable, the two students upstairs release the parachutes at the same time by doing a countdown, 3...2...1...release.  The student outside determines which took the longest to fall.  This student records the fall order on the test sheet with a 1 for the first to fall, a 2 for the second to fall, and a 3 for the last one to fall.  Groups know that a 3 is the best because that means it took the longest to fall which is the purpose of a parachute.  One of the students from upstairs goes down to retrieve the parachutes and brings them back up for a second test.  They do the same procedure 2 more times so that they are testing each variable three times.

It is important to have good behavior management during this process.  Students who are dropping the parachutes cannot play around near the window.  I stood next to the window the entire time so that I could keep a close eye on them.  Our windows only open about half way so falling out is not possible.  If you do not have safe windows in your room or are on the first floor, you could set up two step ladders and have students release parachutes from those.

As you can see in this video of group releasing their parachutes, two students release the parachutes out the window and the third group member is recording the results from outside.  Doing the countdown to drop them at the same time is important because if they aren't dropped at the same time then the results will not be accurate.

## Testing

15 minutes

Connecting this Activity Back to Forces

Before we test our final parachutes, we discuss the relationship this activity has on forces.  The following points are discussed:

• What force is pulling the parachute down? Gravity
• What force acts against gravity to slow down the parachute? Air resistance
• Sometimes I noticed the parachutes did not fall straight, some were spinning, some fell at an angle, some hit the side of the school.  What caused this change in motion? Another force acted on it such as wind.

Testing The Perfect Parachute

The original plan for this was to have groups test their perfect parachutes by sending one person from each group to the window to release their parachute and all other students stand outside to watch to see which hits the ground last.  After watching groups release parachutes during their tests, I realized this would be a very difficult task.  I was not sure how I would get 7 students all up at the window at a time and all 7 students to drop them at the exact same time.  Just two students releasing them a the same time was a struggle.

Since I was not sure the final test would work out, I decided we would just compare the characteristics of the final parachutes and then use them for an egg drop.  The results each group had are below, three groups had the second set of results: medium, paper, circle, 40cm strings.  I thought is was interesting that none of the groups found that squares were better than circles, none found cloth as being the best material, and all groups had 40 cm length strings as the best.

I provided materials such as small cups, cotton balls, duct tape, clay, and tissues for groups to build an egg basket to attach to their parachute.  I gave groups a time limit of 15 minutes to build their basket and attach their parachute.  You can see in this video of students attaching their parachute to their egg drop, that the baskets were not elaborate and the success would depend a lot on the parachute.

We tested each basket one at a time. The ones that protected their egg from breaking moved on to the final round.  I marked a target on the sidewalk below the window for the final round.  The group that got their egg basket closest to the target without their egg breaking in the final round won.