Thermal Protection Systems: Day 1
Lesson 9 of 11
Objective: Students will be able to apply scientific principles to design, construct, and test a device that either minimizes or maximizes thermal energy transfer.
This is Day 1 of a three day lesson in which students explore energy transfer as they use the engineering design process to design thermal protection systems that can prevent a spacecraft from burning up in the atmosphere. This lesson is adapted from NASA's Engineering Design Challenges. Check out the lesson for the upcoming days! It includes explanations of the design process and student work!
This lesson is geared to address the following NGSS and Common Core Standards:
MS-PS3-3 Apply scientific principles to design, construct, and test a device that either minimizes or maximizes thermal energy transfer.
MS-ETS1-1 Define the criteria and constraints of a design problem with sufficient precision to ensure a successful solution, taking into account relevant scientific principles and potential impacts on people and the natural environment that may limit possible solutions.
MS-ETS1-2. Evaluate competing design solutions using a systematic process to determine how well they meet the criteria and constraints of the problem.
MS-ETS1-3. Analyze data from tests to determine similarities and differences among several design solutions to identify the best characteristics of each that can be combined into a new solution to better meet the criteria for success.
MS-ETS1-4. Develop a model to generate data for iterative testing and modification of a proposed object, tool, or process
CCSS.ELA-LITERACY.RST.6-8.1 Cite specific textual evidence to support analysis of science and technical texts.
CCSS.ELA-LITERACY.RST.6-8.7 Integrate quantitative or technical information expressed in words in a text with a version of that information expressed visually (e.g., in a flowchart, diagram, model, graph, or table).
CCSS.ELA-LITERACY.WHST.6-8.9 Draw evidence from informational texts to support analysis, reflection, and research.
Science and Engineering Practices:
As students go through the engineering design process, they create thermal protection systems that can survive traveling through the atmosphere. In doing this, they apply scientific principles to design, construct and test a tool or system (SP6). In addition, students obtain, evaluate, and communicate information such that an optimal design can be achieved (SP8).
Cross Cutting Concepts:
Designing thermal protection systems also can provide students with practice in Cross Cutting Concepts of “Systems and Models” as well as “Energy and Matter”. Students use the thermal protections systems as a model that can show the input and output of energy and track how energy flows within the system (CCC Systems and Models). As they observe the heat transfer in their various designs, they also notice that the transfer of energy can be tracked as energy flows (CCC Energy and Matter).
Ask students, "What are you going to be learning today?". Students should respond with the essential question, "How does energy transfer through various systems in the natural world?" (I keep this posted on the board. Students also have it in their Unit Plan).
Explain that the students will specifically be connecting to Skills 3, 4, and 5 listed in the Unit Plan:
3. I can solve problems based on my understanding of heat transfer (conduction, convection, radiation).
4. I can provide evidence that the amount of energy needed to transfer to change the temperature (average kinetic energy of the particles) of an object depends on the type of matter and the mass of the object.
5. I can support the claim that when the kinetic energy of an object changes, that energy has been transferred to or from the objects in the system (energy is conserved).
At this point, students have already self-assessed their level of mastery on a scale of 1 to 4 (4 being mastery) in the margin for each of these skills. Ask students to reassess themselves and change their number if they feel like their level of mastery has grown. For my students, this is the third lesson dealing with these topics. Thus, I also emphasize that if students feel like their mastery level is not progressing or if they are confused about any topics, now is the time to advocate for themselves and get the extra help they need. Encourage them to ask questions as they work through this design challenge over the next few days to get themselves to a level of mastery they are working towards.
Then, ask the students to make as many connections during the lab to the following ideas/concepts:
- Conduction, convection, and radiation
- How the type of matter or mass of an object affects heat transfer
- How energy can be tracked through a system (that when one object gains energy, another loses energy)
Remind them if at any point during the lab they connect to any of these ideas, they should share that connection with you or a fellow student!
Ask the students to close their eyes and picture a space craft entering or exiting the earth's atmosphere. Allow ample wait time so that the students can all get an image in their heads. Ask students to share their images. Then, ask the students if anyone pictured something such as this:
Explain to students that due to friction in the earth's atmosphere, spacecraft have to have systems in place that can prevent the craft from burning up in the atmosphere. These are called Thermal Protection Systems. Explain that using their knowledge of heat transfer, they will be designing, building and testing their own TPS systems over the next few days using a blow torch to represent the friction in the earth's atmosphere!
Remind the students that engineers always research and back up their ideas with evidence prior to designing. Thus, the students will need to gather some information about important aspects of thermal protection systems.
Side Note: In my class, students have been working throughout this unit on a strategy called "talking to the text". (For some more lessons which introduce this strategy, check out Mystery Box and Heat Transfer.) When students "talk to the text", they mark up the page, underlining, circling, highlighting, and making notes in the margins about connections and questions they make to the text.
Want some buy in for the text the students are about to read? Show them these pictures and explain that the reading is a major factor in the success of their design! Students love that it actually looks like the image they picture in their heads of a spacecraft entering the atmosphere!
Provide students time to individually read this excerpt from a NASA article and talk to the text. This excerpt is a small portion of a full NASA lesson on Thermal Protection Systems. Before beginning let students know that there are certainly words in this NASA article that are challenging; there is a chance they may not understand every word. However, they should talk to the text to make these notations and search for the meaning of these words within the context. In addition, let them know that the purpose of reading this document is to develop a list of criteria that is important for a successful TPS. So, as they read, if they come across something in the text that they think is important to consider when building their own Thermal Protection Systems, they should be sure to note it.
After talking to the text, have students share the criteria they feel will be important in designing a successful thermal protection system. These should be criteria they might consider if creating their own Design Matrix (A design matrix is a way for groups to rank design ideas based on criteria. See this Catapult Lesson or this Earthquake Structure Lesson for more information.) Write this on the board and ask the students to add these suggestions to their Thermal Protection System Design Challenge Student Lab Sheet.
Students typically brainstorm ideas such as:
- Placement of insulators
- Use of conductors away from the space craft
- Consideration of Heat Capacity
- Consideration of Specific Heat
- Use of materials that can burn off or fall away
Remember - this is Day 1 of a three day lesson. To see how to take the students through the full design process, days two and three!
Ask students to recall what a constraint is. Students should respond with "rules and guidelines that must be followed". Provide students with the constraints for this challenge:
1. Designs must last 2 minutes before falling in order to survive through the atmosphere.
2. Students must use a wooden dowel with a screw hot glued to the end in every design.
3. The maximum amount of materials that can be used include: one washer, one nut, one square piece of copper wire mesh, a 4 x 4 inch piece of tin foil, and 4 paper clips (may be bent).
4. Copper wire mesh, tin foil, and paper clips do not have to be used in every design.
5. Nothing can be attached to the wooden dowel other than where the screw head is touching the wooden dowel.
6. Glue may only be placed between the flat part of the crew head and the dowel. (No extra glue may be added to attach any other material.)
7. Time: 3 days (2.5 class periods)
Next, demonstrate for the students how to attach the screw to the dowel.
Then, have students time the baseline design, the control group. The control group is simply the dowel with the screw attached without any other materials.
Have students record this control design to the data table on their lab sheet and talk them through how to fill it out. For the baseline data design, students should simply draw the dowel with the screw attached and record the time of survival. The key to this data table is the third column in which the students analyze the scientific reason why the design was a success or Epic F.A.I.L. (Epic First Attempt In Learning). Students will fill out this table as they make multiple designs.
Next, provide time for students to sketch a design idea. It is important that each design is sketched independently. Next, have students meet in groups of 3 - 4 to discuss their design ideas. Have students make a design matrix with 3 to 4 criteria to make a decision about which prototype to build first. My students are at this point familiar with a design matrix. I ask them to use the class brainstorm to create their own matrix with the criteria they feel is the most important. Students rank each design based on the criteria on a scale of 1 to 4 and decide which design to build first. Below is a student example.
I included this specific matrix that students created for a few reasons:
1. Notice that the students end up in a "tie". At this point, students take the best of all of the designs to create a design that incorporates the best of all of them. (Most designs, however, will have a clear "winner".)
2. The students initially pick their criteria and they are not typically the best criteria to use. I allow them to use these so that they can go through the design process, reflect and adjust along the way. For example, the students chose "ease of construction" and "materials fall away" as criteria. These are just not important criteria for all designs. On the student document in the following days lessons, students will be adjusting the criteria they feel is most relevant.
For some reason, this tends to be students' typical first design.
Students just make a ball of copper and aluminum and stick it on the screw. Although you will want to say, "You are attaching a conductor on top of a conductor connected to the screw; it is not going to work." Don't! Students need to come to this realization on their own! They have more days to come to this conclusion on their own.
On Day 1 of this lesson, students usually only test 1 design or may not even get to the point of testing. In the following days, groups test up to 5 different designs.
Size 6 - 32 Brass Nuts
#6 Brass Washers
Brass Screws (Size 6 x 1)
Copper Wire Mesh (It is sold in 12 x 12 sections, cut this into 12 - 15 sections)
Wooden Dowels (1/4 in birch dowels, purchase longer dowels and cut into 4 inch sticks)
Hot glue gun and glue
What does each design need and what can be reused?
Each design can use up to 4 x 4 inches of aluminum foil, one wire mesh, one dowel, one screw, one washer, one nut, and four paper clips. Other than the aluminum foil, the remainder of the materials can be reused. Keep this in mind when determining how much of each item to purchase. Also, notice that the copper mesh begins to look "worn" after a few uses. It still works! Copper mesh is expensive, reuse it! Also, paper clips can be reused even if they are bent or unwound.
TPS Set Up:
1. Attach test tube clamp to ring stand at the top of the stand.
2. Attach wooden dowel to test tube clamp. Make sure this is kept consistent. Show the students how far back to put the dowel so that this variable can stay constant. It will affect results.
3. Practice lighting the blow torch and place it at a distance where the flame is directly touching the design. Don't feel like you need to make it easier for them. The flame should be directly touching the design! Make a tape mark on the counter so that this distance is consistent.
4. Have a station with all of the other materials organized for student use. Students will be getting their own materials and reusing materials along the way. They do not have their own "set" of materials.
TPS Blow Torch Safety:
1. Goggles must be worn.
2. The teacher is the only person to light the torches.
3. Materials that have been tested will be hot! Simply unscrew the design and let it fall to the table. Leave there to cool. Specifically tell students that they will be tempted to grab their designs once they are done. They need to resist the urge. You, the teacher, will be the one to take these designs apart once they have cooled. Notice in the picture below that there are multiple fallen designs on the counter. I simply leave them where they fall until the cool down enough for me to take them apart to reuse the materials.
All of the information in this section are included in a downloadable word document in the resource section!
During the lab, the students were supposed to be connecting to the following ideas:
- Conduction, convection, and radiation.
- How the type of matter or mass of an object affects heat transfer.
- How energy can be tracked through a system (that when one object gains energy, another loses energy).
Either written on a slip of paper, verbally shared to a partner, or on a whiteboard as a table group, ask students to share a connection they made to each of these ideas in the Thermal Protection Systems Lab. It is important that in this initial lesson that students are able to discuss these as a group or with a partner. This makes the students really have to connect to the key concepts in the lab. Thus, it can be challenging.
In the example above, the students drew a picture of a TPS design and labeled where radiation, conduction, and convection were occurring. Typically, students can come up with where radiation and conduction are but have a greater challenge identifying convection.
For the second point, the group identified that the metal conducted at a greater rate than the wood or air; thus, they have identified that the type of matter affects how kinetic energy is transferred.
Last, the students show that the screw transfers energy to the glue. When the glue gains the energy, the glue melts.