1. To Botswana We go!
In this unit the 5th graders will learn about green engineering and solar ovens. In order to set a backdrop for this lesson, we took a "trip" to Botswana. The STEMmers learned that in this country, fuelwood is the dominant energy source in households. Initially, this source was considered to be free, however, increasingly many of the people have had to purchase wood which is becoming more and more scarce, and therefore more expensive. There is also a growing problem with deforestation which causes people to have to travel farther and farther to gather wood. This can be a big problem if wood is needed to cook for each and every meal. However, organizations have stepped in to introduce and encourage the use of solar ovens in Botswana to make things easier for its citizens and to protect the environment.
The 5th graders will keep these things in mind as they design solar ovens that are effective enough to actually bring the temperature inside of the ovens high enough to actually cook food! However, our focus for this unit is green engineering. This means that their designs should be environmentally friendly, strive to prevent waste, and minimize the depletion of natural resources.
The 5th graders will keep these things in mind as they design solar ovens that are effective enough to actually bring the temperature inside of the ovens high enough to actually cook food! However, our focus for this unit is green engineering. This means that their designs should be environmentally friendly, strive to prevent waste, and minimize the depletion of natural resources.
2. Testing and construction
After getting our background information, the STEmmers formed groups to start on our first step in this unit - testing and constructing. First, the STEMmers used a video to help them construct their solar ovens.
Then, each group worked with a specific material to test its use as an insulator. When it is time to begin planning, the groups will choose insulating materials to go inside of their ovens to help trap the heat. For each test the STEMmers had to place their materials into two cups, laying them flat in one, and shredding it for the other. Then it was time to place the cups in an ice bath. The groups observed and measured the temperatures of the air in their cups every 30 seconds for three minutes. The goal: Find out how well each material works as an insulator to hold heat within a container.
Then, each group worked with a specific material to test its use as an insulator. When it is time to begin planning, the groups will choose insulating materials to go inside of their ovens to help trap the heat. For each test the STEMmers had to place their materials into two cups, laying them flat in one, and shredding it for the other. Then it was time to place the cups in an ice bath. The groups observed and measured the temperatures of the air in their cups every 30 seconds for three minutes. The goal: Find out how well each material works as an insulator to hold heat within a container.
3. Sharing Data
Since each group tested a different material, when all testing was done, the groups recorded the performance of their group's material, and ranked them from best to worst as insulators. These findings will help the groups when they are ready to being planning for their solar ovens.
4. Getting ready for the challenge
In this lesson the 5ht graders did some jigsawing. Each group worked together to specialize in one part of the criteria or scoring for the design challenge, then each group worked together to present that information to the class. Leadership skills definitely has its place in STEM!
5. Adding INsulators
Each group's solar oven box is the same. What will make the difference is which materials each group decides to use as insulators. The teams used the information they learned when testing different insulating materials to choose what they think are the three best materials to help trap the heat in their solar ovens. In their plan the teams decided on which materials to use, how much they would use, and how they would situate each material inside of their solar ovens.
6. Bring on the Sun!
We finally get to test! Each group had their own personal "sun" to use to try to heat their solar ovens. The goal was to have the sun shine on the reflector which would then bounce the light and heat energy inside of the oven through the window. The insulators should have worked to help keep the heat trapped inside. Each group took the initial temperature of their ovens, then every three minutes for 18 minutes to observe any temperature changes.
7. Test & Learn
When we began our lesson today, each team calculated their score. The scores each had two parts.
1. Heat score: The team's maximum temperature reached - the maximum temperature of the control oven
2. The environmental impact score: The focus of this unit is green engineering, so each team needed to balance the effectiveness of their insulating materials with its "greenness" . Teams were rewarded for choosing materials that were natural, and could be reused and recycled. Likewise, they were penalized via extra points for choosing materials that were processed and not environmentally friendly.
After scoring, the STEMmers took a MUSEUM walk. The purpose of this activity was for teams to observe the the different insulating materials other groups used and how they performed. This information will be important as they improve their designs for a second test. The kids did a good job discussing what they thought worked well and what didn't work as well.
1. Heat score: The team's maximum temperature reached - the maximum temperature of the control oven
2. The environmental impact score: The focus of this unit is green engineering, so each team needed to balance the effectiveness of their insulating materials with its "greenness" . Teams were rewarded for choosing materials that were natural, and could be reused and recycled. Likewise, they were penalized via extra points for choosing materials that were processed and not environmentally friendly.
After scoring, the STEMmers took a MUSEUM walk. The purpose of this activity was for teams to observe the the different insulating materials other groups used and how they performed. This information will be important as they improve their designs for a second test. The kids did a good job discussing what they thought worked well and what didn't work as well.