Lesson 9 of 9
Objective: Students will be able to construct, test, and modify a device that either releases or absorbs thermal energy by chemical processes.
In this lesson, students design a warm pack that can keep a bearded dragon warm during transport in our cold Michigan winters. Students choose between a mixture of water and aluminum potassium sulfate or a mixture of water and calcium chloride to provide the warm pack with energy. In addition, students determine the concentration of the mixture and the type of cover material that will maintain the lizards optimal body temperature for the desired period of time.
Specifically, this lesson is designed to address the following NGSS and Common Core Standards:
MS-PS1-6 Undertake a design project to construct, test, and modify a device that either releases or absorbs thermal energy by chemical processes.
CCSS.ELA-LITERACY.WHST.6-8.1.B Support claim(s) with logical reasoning and relevant, accurate data and evidence that demonstrate an understanding of the topic or text, using credible sources.
Science and Engineering Practices:
The NGSS asks that middle school students analyze data to define an optimal operational range for a proposed object, tool, process or system that best meets criteria for success. As students choose the appropriate concentration and cover material for their warm pack that will maintain the temperature at the optimal range for the lizard, they are doing just that! (SP4) In addition to analyzing data, students apply scientific ideas or principles to design, construct, and/or test a design of an object, tool, process or system. (SP6)
The lab document for this lesson is organized by Crosscutting Concept. There is a section about patterns in data, a section asking the students to track the energy as it flows through the system, and another that students explain the cause and effect relationship in their warm pack. There is a section for each Crosscutting Concept in the lab so that students can see how these concepts are truly crosscutting and can all be applied to one scientific model.
Ask students, "What are you going to learn today?" Students should respond by saying that they will be answering the Essential Question, "How do particles combine into new substances? And, what evidence can show how the physical and chemical properties of the substances change?" This EQ is posted on my board and on the student's Chemistry Unit Plan.
As this lesson is the last of the lessons for this unit, have the students read each skill and self assess their level of mastery for each skill in the Chemistry Unit Plan. After reading the skill have the students rank their current level of mastery on a scale of 1 to 4 (4 being mastery).
In my classroom, students frequently self-assess their level of understanding on each skill in the unit as we go. As you can see from the image below, this student ranks himself as a "3" to start this lesson. With each lesson, students re-assess where they are in terms of their own level of mastery.
*Students in my class have already gone through several lessons about chemical reactions and properties. I have included these notes pages in the resource section so you can have an idea of where we have been prior to this lesson!
For a look at all the lessons that have led my students to this point and where we go from here check out the lessons in these units:
Physical Properties: Molecular Arrangement and Phase Changes: Focuses on Skills 1 - 4 of the Chemistry Unit Plan
This unit is designed to answer the Essential Question, "How do particles combine into new substances? What evidence can show how the physical and chemical properties of the substances change?" It particularly focuses on types of matter, physical properties, phase changes, and factors that affect physical properties. This unit's purpose is so much more than just the content, however. It's focus is scientific literacy. It stresses group discussion, discourse and utilizing text references when engaging in argument. Students utilize reading, writing, and speaking strategies in order to develop scientific literacy. It's scientific literacy immersion!
Chemical Properties and Reactions: Focuses on Skills 4 - 6 of the Chemistry Unit Plan.
This unit is also designed to answer the Essential Question, "How do particles combine into new substances? What evidence can show how the physical and chemical properties of the substances change?" This unit focuses on chemical properties and chemical reactions. Students analyze evidence and property changes that allow them to distinguish between chemical and physical reactions. In addition, students investigate the Law of Conservation of Mass as they look at how bonds are broken and formed in chemical reactions. This unit is full of hands on labs and station rotations that will engage any middle school student in chemistry!
I begin by having the students read the introduction to the Lethargic Lizard, which reads:
"Mrs. Roehm has a bearded dragon named Iggy. Mrs. Roehm is considering having Iggy as a school pet. However, in order to be able to feed him during holiday breaks, she will need to be able to transport him back and forth from her house to school during the cold winter months. Mrs. Roehm would like you to design a warm pack that she can put in the bottom of his cage to keep him warm when she carries him back and forth during the winter. Read the article about bearded dragons to learn more about the way their bodies work."
I then have the students read Bearded Dragons: Cold-blooded Companions to learn more about how they are affected by temperature changes and to investigate the optimal body temperature for a bearded dragon.
I explain that during this lab, they will continue to connect to the NGSS Crosscutting Concepts. I remind them that these concepts can help us think deeply about science and engineering as they are truly crosscutting - they can be applied across science disciplines. I ask them to look at the organization of their lab document to notice that there is a section for each crosscutting concept.
Before moving forward, I explain that it is important that they as students have an understanding of what these concepts mean. I assign each table a crosscutting concept. I ask them to read the heading for that concept in their Lethargic Lizard Lab, their Ladder of Discourse Description of Rungs, as well as their Working Towards Discourse document.
In addition, I provide them with the NGSS Crosscutting Concepts. I explain that as a teacher, this is the information that I received about each concept. I explain that the wording on this document can be challenging for 7th graders. In their groups, I ask them to come up with a description for their assigned concept that would help another 7th grader understand what it means. I let students know that they will then be describing their description of the concept to the class.
After providing students time to discuss, each group shares to the whole group about the meaning of the crosscutting concept they investigated.
The Lethargic Lizard
I remind students that engineers work with constraints, or rules/guidelines that they must follow. I review with the class the constraints for this activity.
- Warm packs must be contained in a Ziploc bag.
- Warm packs can only use either aluminum chloride or calcium chloride.
- Warm packs must be covered with either tin foil or paper.
- Cost must be held at a minimum. No more than 3 teaspoons of any chemical may be used.
- Warm packs must be designed within 2 class period.
- The temperature of the warm pack must remain in the range of temperatures appropriate for Iggy: 35˚C to 42˚C
- The temperature of the warm pack must remain within the desired range for 5 minutes.
Step 1: Choosing a Chemical and a Concentration
- Add 50 ml of water to three beakers of water.
- Add 1 teaspoon of Aluminum Potassium Sulfate to the first beaker and stir with a stirring rod.
- Add 2 teaspoons of Aluminum Potassium Sulfate to the second beaker and stir with a stirring rod.
- Add 3 teaspoons of Aluminum Potassium Sulfate to the third beaker and stir with a stirring rod.
- Add a thermometer to each beaker.
- After 3 minutes, measure the temperature. During the three minutes, stir the solution periodically but do not leave the stirring rod in the liquid the entire time or stir it the entire time.
- Record the data below.
- Rinse out the three beakers thoroughly.
- Repeat Steps 1 – 8 using Calcium Chloride instead of Aluminum Potassium Sulfate.
Students find that aluminum potassium sulfate decreases the temperature while adding calcium chloride increases the temperature. In addition, students find that 2 teaspoons of calcium chloride is the appropriate concentration of the chemical mixture. Adding 1 teaspoon does not increase the temperature enough to fit in the lizard's optimal range and 3 teaspoons increases the temperature above the optimal temperature range. Below the student describes the how they came to this conclusion.
Step 2: Choosing a Material for the Cover of the Warm Pack
1. Put a Ziploc bag in a paper “sleeve”. Teacher Tip: I simply use duct tape and paper towel to make a "sleeve" that can fit the zip lock bag.
2. Add the chemical type and amount chosen in the previous sections inside the Ziploc bag.
3. Add 50 mL of water to the Ziploc bag. Swirl the liquid in the bag back and forth.
4. Quickly close the zip lock bag and “seal”/close the “sleeve” as well. Hold the thermometer so that the tip is touching where the mixture in the bag is. Fold the “sleeve” slightly around the thermometer and pinch with your fingers just above where the liquid in the bag is. Measure the temperature every minute for 5 minutes. Hold in this manner for the entire 5 minutes. Safety Alert: The bags may get hot! Wear gloves and pinch ABOVE the liquid level. Record the data in the table below.
5. Repeat Steps 1 – 4 with a tin foil “sleeve”. (Feeling ambitious? Want to save time? Have your group set up both sleeves at the same time!)
After completing both procedures, provide students with time to complete the lab questions.
Stay Tuned: After completing this lesson, I realized its potential for an extension/application that would allow students more freedom in their designs. After determining the characteristics that meet the criteria for the warm pack in this lesson, I am working on adding a section in which the students then take into account cost and design characteristics to develop a marketable warm pack. Student work demonstrating this is coming soon!
For a closer look at how the students connect to the crosscutting concepts in the lab, take a look at the student work below.
In the "Scale, Proportion, and Quantity" section, students note that increasing the quantity of the calcium chloride increases the temperature. In addition, they explain that two teaspoons of calcium chloride is the appropriate quantity as it is the only choice that falls within the optimal range for the bearded dragon.
In the "Patterns" section, students notice that each time aluminum potassium sulfate was added, the temperature decreased below room temperature. Calcium chloride increased the temperature. This student also notices that as more calcium chloride is added, the higher the temperature. In addition, this student showed that she is deeply looking at the data as she recognizes that the calcium chloride data is linear and increases at the same rate with a 1 teaspoon increase in calcium chloride.
In the "Cause and Effect" section, students recognize that the calcium chloride was undergoing a chemical process that caused a release in energy when bonds were broken and formed.
In this section, students recognize that the chemical reaction and the sleeve work together in a system. Moreover, they notice that the structure of the warm pack serves its function as the paper is an insulator that won't conduct energy as quickly as the tin foil allowing it to remain in the lizard's optimal temperature range.
In the "Stability" section, students recognize that the warm pack will eventually reach a stable temperature. The student cites data that demonstrates that the temperatures increased and then decreased over time. They note that the molecules will keep transferring energy to their surroundings until they reach an equilibrium.
In the "Energy and Matter" section, the student drew a diagram tracking the energy transfer and the types of energy in the system. The student notes that chemical energy is transformed into thermal energy and that the energy is transferred through the bag and into the lizard. In addition, in the second question, the student explains that the mass of the bag was the same before and after the reaction due to the Law of Conservation of Mass.
To close, have the students as a group discuss how the Lethargic Lizard Lab connected to the NGSS Crosscutting Concept that they described to the class in the Mini Lesson. Then, have each table group share with the class their connections. After each group presents, offer to the whole class the opportunity to add any connections that they made to that concept that the presenting group may not have shared.
I then close by saying something like, "Notice that in one lab, the Lethargic Lizard Lab, we can connect to each of these concepts. That is what crosscutting means. They can be applied throughout science topics and phenomena. As you read, write, and form conclusions in science, keep these crosscutting concepts in your mind. Connecting to these concepts, no matter the focus topic, can help you develop a deeper understanding!"