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.
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.
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:
*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.
Determining What Affects the Fall Time of a Parachute
I begin by telling students that I went skydiving about 8 years ago. I tell them that I flew up in a plane and then jumped out. I ask what they think happened when I jumped from the plane. They tell me I fell through the sky. I asked them why I was falling? They tell me gravity was pulling me down towards Earth. Since I didn't fall all the way to the ground, I ask them what they think was used to slow me down? Students tell me a parachute. I use this time to review matter and that there are particles in the air that push against the parachute to help it work against the force of gravity and slow me down.
I show the class the Parachute Diagram on the overhead. The diagram labels the canopy, lines, and load as the major parts of a parachute. I point these items out to the students without going into too much detail about them because I want them to determine on their own how each item affects the descent of the parachute.
I ask students what changes could be made to a parachute that might affect how fast or slow it falls. Students tell me the size of the canopy, the weight of the load, and the shape of the canopy. Since the lines are the only thing they did not comment on, I ask them what could be changed about the lines that might affect it. One student tells me the number of lines, another tells me the materials used, and another tells me the length of the lines.
I provide each group with a whiteboard and marker and assign each group with one of the changes the class identified above and have the group brainstorm how it may affect the fall of the parachute. Group one brainstormed how different canopy materials might affect the fall. Group two brainstormed how he weight of the load would impact the fall. Group three brainstormed how the shape of the canopy might impact it. Group 4 brainstormed how changing the lines might impact the fall. As each group shares their ideas, we discuss them.
After our discussion, I tell students that today they will be building parachutes changing some of the things they just identified, trying to create the best parachute.
Why have them Identify the Changes
I already have specific things set for students to change and test in order to create their parachute. Although I already have these items selected, it is important to have the conversation above with students because it allows them to come up with these ideas on their own. I can guide the conversation, just like I had to with the changes to the lines, but they are still thinking scientifically to come up with changes that would impact the fall time. Students take more ownership in the project when they think they are the ones that have developed it. They also retain information better when they have to develop their own reasoning, rather than me just telling them.
Reviewing the Task Sheet
I place the Engineering Design Project - Parachute Task Sheet on the overhead and go over the goal and limitations. I explain to students that the parachutes will be tested by being dropped out the classroom window and timed to see how long it takes to fall to the ground.
Next, I place the Parachute Planning and Testing Sheet on the overhead because it is different from the normal engineering planning sheet we use. I go over each test with the class answering questions as we go. Students are allowed to begin with any test they would like but must complete all of them in order to develop the best parachute.
As I go over the planning sheet, I make sure to go into detail how they should go about testing each. I make it clear that they can only test one thing at a time, the things they are not testing should be set at the middle option. For example, if a group wants to start with the shape of the canopy, I tell they they would need to build a parachute with 40 cm line, a medium circle canopy out of paper and a medium square canopy out of paper. 40 cm is the middle length, and the medium size is also in the middle. Paper is the cheapest for me to replace so they can cut as many canopies from paper as they would like so I want them always using paper until they are testing the material. After they figure out if the circle or square shape is the best, they will keep that shape constant and change another variable.
After reviewing the planning sheet and checking for understanding, I place the Engineering Design Process on the overhead to review with them. I point out that they cannot test more than one thing at a time or they will not get accurate results. For example, they cannot change the size of the canopy and the length of the lines at the same time. They will need to leave the lines the same as they are changing the size of the canopy in order to determine which canopy size is best. I tell them that we are skipping the research section of this project because I have already done the research for them. I looked up a variety of parachutes to see variations. I also looked up the parts of a parachute and how changes affect the fall time. I share some of my research with them, using the Research for What Affects Parachute Fall Time PowerPoint. I do not provide them with too much information, just a little background knowledge on how parachutes have changed over time that may help guide them when making their predictions. Groups will begin with the planning step for this activity instead of the research to save time.
Planning and Building
I allow students to choose their groups for this project instead of assigning them. I do this because there are numerous different changes and tests that are going to be taking place and I want them to be working in groups with people I know they can get along with. When they choose their own groups, they choose students they know they can work well with. I do remind them not to choose a group they think they will play around in. I circulate the entire time to make sure they stay on task and are doing the right thing.
Students spend the first 5 minutes planning, which really just requires them to make their predictions and decide what they will be starting with. Groups show me their plan prior to beginning.
When they come up to show me their plan, I ask them to review with me what the process is going to look like for their group. If a group is beginning with the shape of a canopy, I am checking that they understand the process will be something like this:
It is important to know that students understand the process before beginning. It took some groups several attempts before they could explain the process correctly to me. In the video of group explaining test incorrectly, you can hear that they change all variables in their explanation instead of just one item at a time. The group in the video of group explaining test correctly, they change only the size of the parachute keeping all variables the same which is correct. Once their plan is approved and it is clear they know the process they will be following, they get the materials they need for their first test and get started measuring and building their parachute. Most groups only have time for one test today, they finish the rest on day 2 of the lesson tomorrow.
The group in the video of group building parachute, is working on assembling their square, plastic parachute. After completing the other 2 parachutes, they will complete their first test. The picture below shows another group measuring out their strings before they begin assembling their parachutes for their first test.