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Systems and Scale Unit, Lesson 4 Carbon: Transformations in Matter and Energy 2019 Michigan State University
Lesson 4: Investigating and Explaining Ethanol
Burning
Overview
Students investigate changes in mass and CO 2 concentration for burning ethanol. Then they explain results using molecular models and chemical equations to answer the Three Questions.
Guiding Question
What happens when ethanol burns?
Activities in this Lesson
- Activity 4 .1: Predictions about Ethanol Burning ( 3 0 min)
- Activity 4 .2: Observing Ethanol Burning (30 min)
- Activity 4.3: Evidence-Based Arguments about Ethanol Burning (50 min)
- Activity 4.4: Molecular Models for Ethanol Burning (50 min)
- Activity 4.5: Explaining Ethanol Burning (40 min)
Unit Map
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Systems and Scale Unit, Lesson 4 Learning Goals
Target Performances
Activity Target Performance
Lesson 4 – Investigating and Explaining Ethanol Burning (students as explainers) Activity 4.1: Predictions about Ethanol Burning (30 min) Students develop hypotheses about how matter moves and changes and how energy changes when ethanol burns and make predictions about how they can use their investigation tools—digital balances and BTB—to detect movements and changes in matter. Activity 4.2: Observing Ethanol Burning (30 min) Students record data about changes in mass and BTB when ethanol burns and reach consensus about patterns in their data. Activity 4.3: Evidence-Based Arguments about Ethanol Burning ( min) Students (a) use data from their investigations to develop evidence-based arguments about matter movements, matter changes, and energy changes when ethanol burns; and (b) identify unanswered questions about matter movement, matter change, and energy change that the data are insufficient to address. Activity 4.4: Molecular Models for Ethanol Burning (50 min) Students use molecular models to explain how carbon, oxygen, and hydrogen atoms are rearranged into new molecules during the oxidation of ethanol (the chemical change that happens when ethanol burns). Activity 4.5: Explaining Ethanol Burning (40 min) Students explain how matter moves and changes and how energy changes when ethanol burns (connecting macroscopic observations with atomic- molecular models and using the principles of conservation of matter and energy).
NGSS Performance Expectations
Middle School
- Structures and Properties of Matter. MS-PS1-1. Develop models to describe the atomic composition of simple molecules and extended structures.
- Chemical Reactions. MS-PS1-2. Analyze and interpret data on the properties of substances before and after the substances interact to determine if a chemical reaction has occurred.
- Chemical Reactions. MS-PS1-5. Develop and use a model to describe how the total number of atoms does not change in a chemical reaction and thus mass is conserved. High School
- Chemical Reactions. HS-PS1-4. Develop a model to illustrate that the release or absorption of energy from a chemical reaction system depends upon the changes in total bond energy.
Systems and Scale Unit, Lesson 4
- In systems like our atmosphere, where excess oxygen is always present, the most abundant sources of chemical energy are substances that release energy when they are oxidized (e.g., substances with C-C and C-H bonds). Our research has consistently showed that these ideas are extremely difficult for students who have not formally studied chemistry. We therefore use the convention of twist ties to identify bonds that release energy when they are oxidized. The investigations in all units will make use of two essential tools:
- Digital balances. Students can detect movement of atoms (the Matter Movement Question) by measuring differences in mass. In this activity students will be able to observe changes when ethanol is burned.
- Bromothymol blue (BTB) is an indicator that changes from blue to yellow in response to high levels of CO 2. Thus, changes in BTB can partially answer the Matter Change Question by detecting whether there is a chemical change that has CO 2 as a reactant or product.
Key Ideas and Practices for Each Activity
Activity 4.1 is the Predictions and Planning Phase of the instructional model (beginning the climb up the triangle). During this phase, students record their predictions and express ideas about what happens to matter when ethanol burns. They use the Predictions and Planning Tool to do this. Activity 4.2 is the Observations Phase of the instructional model (going up the triangle). During this phase, the students conduct the investigation for ethanol burning, record data, and try to identify patterns in their data and observations. The important practices students focus on in this activity are 1) making measurements and observations, 2) recording their data and evidence, and 3) reaching consensus about patterns in results. They use the Observations Worksheet and Class Results Poster to do this. Activity 4.3 the Evidence-Based Arguments Phase of the instructional model (going up the triangle). During this phase, the students review the data and observations from their investigation of ethanol burning and develop arguments for what happened during the investigation. In this phase, they also identify unanswered questions: at this point they have collected data and observations about macroscopic scale changes (BTB color change and mass change), but they do not have an argument for what is happening at the atomic-molecular scale. They use the Evidence-Based Arguments Tool to record their arguments at this phase. Activity 4.4 is the first part of the Explanations Phase of the instructional model (going down the triangle). Students construct molecular models of the chemical change they observed in the investigation to help them develop an atomic-molecular explanation for what happened. Activity 4.5 the second part of the Explanations Phase of the instructional model (going down the triangle). Students use the Explanations Tool to construct final explanations of what happens when ethanol burns. Ideally, at this phase their explanations will combine evidence from macroscopic-scale observations during the investigation with their new knowledge of chemical change at the atomic-molecular scale. Key carbon-transforming processes: combustion
Content Boundaries and Extensions
Talk and Writing At this stage in the unit, students will complete the inquiry and application sequences for ethanol burning—they go both up and down the triangle. This means that they will go through the
Systems and Scale Unit, Lesson 4 Predictions Phase, the Observations Phase, the Evidence-Based Arguments Phase, and the Explanations Phase in one lesson. The tables below show specific talk and writing goals for these phases of the unit. Talk and Writing Goals for the Predictions Phase Teacher Talk Strategies That Support This Goal Curriculum Components That Support This Goal Treat this as elicitation and brainstorming (like the Expressing Ideas and Questions Phase), but with more directed questioning. Now that we have set up the investigation, we want to predict what we think will happen to matter and energy. Three Questions Handout Predictions and Planning Tool Elicit a range of student ideas. Press for details. Encourage students to examine, compare, and contrast their ideas with the ideas of other students. Who can add to that? What do you mean by _____? Say more. So I think you said _____. Is that right? Who has a different idea? How are those ideas similar/different? Who can rephrase ________’s idea? Investigation Video (first half) Encourage students to provide evidence that supports their predictions.. How do you know that? What have you seen in the world that makes you think that? Have students document their ideas to revisit later. Let’s record our ideas so we can come back to them and see how our ideas change. Predictions and Planning Tool Talk and Writing Goals for the Observations Phase Teacher Talk Strategies That Support This Goal Curriculum Components That Support This Goal Help students discuss data and identify patterns. What patterns do we see in our data? How do you know that is a pattern? What about ______ data. What does this mean? Class Results Poster Class Results Spreadsheet Encourage students to compare their own conclusions about the data and evidence with other groups and other classes. What about this number? What does this tell us? How is group A’s evidence different from Group B’s data? How do our class’s data differ from other classes’ data? Class Results Spreadsheet Class Results Poster Investigation Video (second half). Make connections between the observations and the data/evidence. It says here that our BTB turned colors. What does that mean? You recorded that your ethanol lost weight. What does that mean? Have students consider how their predictions and results compare. Let’s revisit our predictions. Who can explain the difference between our class predictions and our results? Who had predictions that were similar to our results? Has your explanation changed? How? Talk and Writing Goals for the Evidence-Based Arguments Phase Teacher Talk Strategies That Support This Goal Curriculum Components That Support This Goal Press for details. Encourage students to examine, compare, and contrast their ideas with the ideas of other students. Who can add to that argument? What do you mean by _____? Say more. So I think you said _____. Is that right? Who has a different argument? How are those arguments similar/different? Investigation Video (second half)
Systems and Scale Unit, Lesson 4 compare, and contrast their explanations with others’. Who can rephrase ________’s explanation?
Systems and Scale Unit, Lesson 4 Activity 4.1: Predictions about Ethanol Burning (30 min) Overview and Preparation
Target Student Performance
Students develop hypotheses about how matter moves and changes and how energy changes when ethanol burns and make predictions about how they can use their investigation tools— digital balances and BTB—to detect movements and changes in matter.
Resources You Provide
- (From previous activity) Students’ ideas and questions they shared in Activity 1. Expressing Ideas and Questions Tool for Ethanol Burning
- (From previous activity) 1.2 Expressing Ideas and Questions Tool for Ethanol Burning
- Video or demonstration of ethanol burning
Resources Provided
- 4.1 Predictions about Ethanol Burning PPT
- 4.1 Predictions and Planning Tool for Ethanol Burning (1 per student)
- 4.1 Assessing the Predictions and Planning Tool for Ethanol Burning
- 4.1 Good Explanations of Chemical Change Reading (1 per student)
Recurring Resources
- Three Questions 11 x 17 Poster (1 per class)
- Three Questions Handout (1 per student)
- Questions, Connections, Questions Student Reading Strategy
- (Optional) Investigation Planning Tool
- Burning Ethanol Video
Setup
Print one copy of 4.1 Predictions and Planning Tool for Ethanol Burning, 4.1 Good Explanations of Chemical Change Reading, and Three Questions Handout for each student. Prepare a computer and projector to display the PPT and the video. Print one copy of the Three Questions 11 x 17 Poster and display it on your classroom wall. Retrieve the materials from Activity 1.2. This may include a PPT slide from the lesson in which you typed students’ responses or a photograph of their sticky notes as well as the students’ completed 1.2 Expressing Ideas and Questions Tool for Ethanol Burning. Directions
1. Use the instructional model to show students where they are in the course of the unit. Show slide 2 of the 4.1 Predictions about Ethanol Burning PPT.
Systems and Scale Unit, Lesson 4
6. Discuss the Matter Movement Question as it relates to a digital balance Show slides 7 and 8 of the 4.1 Predictions about Ethanol Burning PPT. Discuss with students how a digital balance can be used to measure matter moving into or out of a system. Highlight that the mass of the system can be measured before and after a change happens in a system. Discuss the two possible conclusions students can draw from their observations:
- If the mass of the system increases, then matter must have moved into the system (remember the facts about atoms)
- If the mass of the system decreases, then matter must have moved out of the system. 7. Discuss Matter Change Question as it relates to BTB Show slide 9 of the 4.1 Predictions about Ethanol Burning PPT. Discuss with students how BTB can be used to measure matter change in a system. Highlight that the BTB in a closed container can be observed before and after a change happens in the system. Discuss the two possible conclusions students can draw from their observations:
- If the BTB changes from blue to yellow, then a chemical change may be producing CO 2
- If the BTB changes from yellow to blue, then a chemical change may be using CO 2 as a reactant. 8. Have students complete their predictions for Ethanol Burning: Part B of the Predictions and Planning Tool. Show slide 10 of the PPT. Have students find Part B on 4.1 Predictions and Planning Tool for Ethanol Burning and ask them to record their ideas as individuals for the matter movement, matter change, and energy change questions. Remind students that these are just predictions , and that there are no wrong answers at this point. Encourage them to write down all their ideas on the tool. Divide students into pairs and tell them to compare and contrast their predictions with each other and to look for differences and similarities. Give students 2 - 3 minutes to compare their predictions**.
- Save the Predictions and Planning Tools for later.** Display slide 11.
- Tell students that tomorrow they will discuss their predictions together as a class.
- Also, they will revisit their ideas after the investigation to see how their ideas changed over time
Systems and Scale Unit, Lesson 4
10. Have students share ideas about planning the investigation: Part C of the Predictions and Planning Tool. Show slide 12 of the PPT and describe the instruments and materials necessary for carrying out the investigation. Have students begin planning their investigation. There are two main variations in how much control students can have over this planning process:
- Minimal student control: Discuss student ideas for how an investigation could be set up. Then have students follow the lab instructions for lesson 4.
- Maximal student control: Students in the class develop their own consensus plans that will replace the lab instructions in lesson 4.2. (They may use the Investigations Planning Tool for making their plans. Note the importance of having different student groups following the same plan so that they can come to a consensus about patterns in data in lesson 4.2 Some possible ideas of using lab materials are below.
- Students might choose to add controls to the experiment, for example including both a Petri dish of yellow bromothymol blue (BTB) (made from blowing into the blue BTB with a straw) and a Petri dish of blue BTB to the chamber.
- Students might also choose to set up a chamber with a Petri dish of blue BTB alone without the ethanol. Assessment The Three Questions will be new to students, and Level 2 students will find the questions themselves hard to understand. In particular, they will initially be unable to connect the three columns in the Three Questions 11 x 17 Poster:
- The question itself: Note whether students use the “Facts about atoms and molecules” that they studied in Lesson 2 as they try to answer the Matter Movement and Matter Change Questions.
- Rules to follow: The most important rule (and the first Fact about Atoms) is: Atoms last forever. Do they follow that rule when they try to answer the questions?
- Evidence to look for: Students will address this column in more depth when they do the investigation. One thing to note for now: Do students connect the ethanol losing mass with atoms leaving the ethanol?
- During the class, listen to the idea’s students offer in the final step of the activity. At this point, do students’ predictions follow the rules? At this point, do not correct student ideas, but listen for what they say about matter and energy in the context of combustion. After class, use the 4.1 Assessing the Predictions and Planning Tool for Ethanol Burning to compare your students’ what we would expect to see in Level 4 responses. This discussion will show that some students are still at Level 2 with respect to both their ideas about energy and their understanding of the questions. For example, do students have a sense of necessity about the connections between mass changes and movement of atoms? Do they recognize that if the ethanol loses mass, then atoms must be moving out of the ethanol? Do students account for energy separately from matter, or do they suggest that some of the matter in the ethanol might be converted to energy? You do not need to correct any problems now; they will be addressed through the investigation and Modeling in the Activities to come. Differentiation & Extending the Learning
Differentiation
Systems and Scale Unit, Lesson 4
Activity 4.2: Observing Ethanol Burning (30 min)
Overview and Preparation
Target Student Performance
Students record data about changes in mass and BTB when ethanol burns and reach consensus about patterns in their data.
Resources You Provide
- BTB, blue (less than 1 cup per group)
- (optional) BTB, yellow (less than 1 cup per group)
- digital balance (1 per group of four students)
- ethanol, 95% (10-15 ml per group)
- large plastic container with aluminum foil taped inside to protect the bottom from the ethanol flame (1 per group of four students)
- lighter (1 per group of four students)
- Petri dish, glass (1 per group of four students)
- Petri dish, plastic (1 per group of four students)
- safety glasses (1 per student)
- (Optional) Molecular modeling kits
- (From previous activity) 4.1 Predictions and Planning Tool for Ethanol Burning with student answers NOTE: Some classrooms have access to CO 2 probes. We designed this investigation with BTB because it is less expensive than probes, but if you have them available, they are more sensitive than BTB and show changes more quickly.
Resources Provided
- 4.2 Ethanol Burning Class Results 11 x 17 Poster (1 per class)
- 4.2 Ethanol Burning Class Results Spreadsheet (1 per class)
- 4.2 Observing Ethanol Burning Worksheet (1 per student)
- 4.2 Grading the Observing Ethanol Burning Worksheet
- 4.2 Observing Ethanol Burning PPT
Recurring Resources
- Three Questions Handout (1 per student)
- (Optional) BTB Color Handout
- (Optional) BTB Instructions and Information Handout
- Burning Ethanol Video
Setup
Prepare the BTB, Petri dishes, ethanol, lighter, digital balances, plastic containers, aluminum foil, and safety glasses for students to retrieve for their groups. If you plan to use the poster to record student data, print one copy of the poster before class and post it on the wall. Print one copy of 4.2 Observing Ethanol Burning Worksheet for each pair of students. Prepare a computer with an overhead projector to display the PPT and video. You may want to review the BTB Instructions and Information Handout and/or print a few color copies of the BTB Color Handout for students.
Systems and Scale Unit, Lesson 4 Directions
1. Use the instructional model to show students where they are in the course of the unit. Show slide 2 of the 4.2 Observing Ethanol Burning PPT. 2. Have students set up the investigation. Display slide 3 of the 4 .2 Observing Ethanol Burning PPT. Divide students into groups of four.
- Pass out one copy of 4 .2 Observing Ethanol Burning Worksheet to each student. Walk through the steps in Part A of the worksheet that overview how to set up and conduct the investigation. 3. Have students conduct the investigation. Display Slide 4 while students are conducting the investigation. The students will need to wait 20 minutes to see color change in the BTB. 4. Have students discuss their predictions about the Matter Movement Question as a class. While waiting for the ethanol to burn, display slide 5 of the PPT. Ask students to retrieve their completed tools from the previous activity: 4 .1 Predictions and Planning Tool for Ethanol Burning.
- Ask pairs of students to share their ideas for the Matter Movement Question. Ask students what they expect to see in the investigation and what that might mean.
- Use the Three Questions Handout to check if students’ predictions follow the rules. If they don’t, ask students why they don’t. At this stage, students’ ideas do not yet need to be corrected.
- Record students’ ideas on the slide.
- Help the students look for similarities and differences in the predictions in the class. Try to get a range of ideas on the slide. 5. Have students discuss their predictions about the Matter Change Question as a class. While continuing to wait for the ethanol to burn, display slide 6 of the PPT and ask pairs of students to share their ideas for the Matter Change Question.
- Lead a discussion by asking students what they expect to see in the investigation and what that might mean.
- Use the Three Questions Handout to check if students’ predictions follow the rules. If they don’t, ask students why they don’t. At this stage, students’ ideas do not yet need to be corrected.
- Record students’ ideas on the slide.
- Help the students look for similarities and differences in the predictions in the class. Try to get a range of ideas on the slide. 6. Have students discuss their predictions about the Energy Change Question as a class. While continuing to wait for ethanol to burn, display slide 7 of the PPT and ask pairs of students to share their ideas for the Energy Change Question.
- Lead a discussion by asking students what they expect to see in the investigation and what that might mean.
Systems and Scale Unit, Lesson 4
- Ask students to compare the colors they observed with the colors from Ms. Angle’s class. What similarities or differences do they notice? 13. Revisit predictions from the previous activity. Use slide 14 to revisit students’ predictions from Activity 4.1.
- Have them compare the predictions they made with the results of the investigation.
- Which predictions were correct? Which predictions were incorrect? What questions to they still need to answer? 14. Have students complete an exit ticket. Show slide 15 of the 4.2 Observing Ethanol Burning PPT.
- Conclusions: What did you observe during the investigation?
- Predictions: What do you think is one conclusion you can make from the investigation?
- On a sheet of paper or a sticky note, have students individually answer the exit ticket questions. Depending on time, you may have students answer both questions, assign students to answer a particular question, or let students choose one question to answer. Collect and review the answers.
- The conclusions question will provide you with information about what your students are taking away from the activity. Student answers to the conclusions question can be used on the Driving Question Board (if you are using one). The predictions question allows students to begin thinking about the next activity and allows you to assess their current ideas as you prepare for the next activity. Student answers to the predictions question can be used as a lead into the next activity. Assessment Use the class discussion to interpret how successful your students are at identifying patterns in the class data. Use the 4.2 Grading the Observing Ethanol Burning Worksheet to determine if your students had any trouble with data collection. During this Activity, note students' success in measuring changes in mass and BTB. Also note students' ability to reach a consensus about patterns in data and how they interpret results. Differentiation & Extending the Learning
Differentiation
Modifications
- Have students develop the experimental design on their own using the tools provided. For example, students may choose to set up a control treatment as a chamber with BTB and no ethanol.
- If you have a hygrometer, consider measuring water content in the air after the ethanol burns.
Tips
Addressing problems at this point as students try to find patterns in data will support their learning in future investigations. This is the first investigation, so it is likely to expose challenges that may come up again.
Systems and Scale Unit, Lesson 4
Extending the Learning
Students can explore conditions under which the ethanol burns for longer or shorter periods, and the relationship between how long the ethanol burns and how much mass it loses.
Systems and Scale Unit, Lesson 4
3. Have students share ideas about the chemical change with ethanol burns Display slide 4 of the 4.3 Evidence Based Arguments Tool. Pass out the 3.3 Evidence Based Arguments Tool Worksheet. Have students complete and discuss part A of the tool. Have students discuss how their ideas have changes since they wrote about ethanol burning on the predictions and planning tool. 4. Have students develop arguments for what happened as individuals. Display slide 5 of the 4.3 Evidence-Based Arguments Tool for Ethanol Burning PPT. Pass out one copy of 4 .3 Evidence-Based Arguments Tool for Ethanol Burning to each student. Review Tool directions. Also, have students take out their Three Questions Handout and be ready to refer to their class results.
- Instruct students to complete their evidence, conclusions, and unanswered questions as individuals for the Three Questions.
- Give students about 5-10 minutes to complete the process tool. 5. Have students compare and revise arguments in pairs. Display slide 6 of the 4.3 Evidence-Based Arguments Tool for Ethanol Burning PPT. Divide students into pairs.
- Have each pair compare their evidence, conclusions, and unanswered questions for the Matter Movement Question.
- Have partners discuss how their ideas are alike and different. Have students change or add to their responses, based on partner input.
- Have students repeat this step for the Matter Change Question and the Energy Question.
- Pay attention to patterns in students’ ideas. You will want to begin moving towards class consensus in this activity.
- Partner work should take about 10 minutes. 6. Have a class discussion of the Matter Movement Question; move toward class consensus. Display slide 7 of the 4.3 Evidence-Based Arguments Tool for Ethanol Burning PPT.
- Have students/pairs share their evidence and conclusions for the Matter Movement question. Keep a class record, using the PPT slide or board. Ask students to update their answers by using a different colored writing utensil. Discussions should move toward class consensus. Use class conversation to correct student ideas. Use the Three Questions Handout to help guide towards consensus by following the established rules.
- Have students share unanswered questions. Discussions should move toward class consensus. Use the 4.3 Assessing the Evidence-Based Arguments Tool for Ethanol Burning to guide your goals for consensus. Note that students may contribute unanswered questions that align with rules on the Three Questions Handout but may not closely align with those on the Assessing worksheet. You may still choose to record those unanswered questions. These may be answered in other parts of this unit or even in other units during the school year. However, at this point in this unit, though there may be several viable paths of inquiry moving forward, you will begin to more closely guide the path of inquiry in one direction – in this case towards molecular modeling of ethanol burning.
- Class discussion should take about 10 minutes. 7. Repeat step 5 with the Matter Change Question; move toward class consensus. Display slide 8 of the 4.3 Evidence-Based Arguments Tool for Ethanol Burning PPT.
Systems and Scale Unit, Lesson 4
- Class discussion may take another 10 minutes. 8. Repeat step 5 with the Energy Change Question; move toward class consensus. Display slide 9 of the 4.3 Evidence-Based Arguments Tool for Ethanol Burning PPT.
- Class discussion may take another 10 minutes. 9. Discuss how the Unanswered Questions shape our next steps, and the transition from inquiry to application. Display slide 10 of the 4.3 Evidence-Based Arguments Tool for Ethanol Burning PPT.
- Use the Unanswered Questions to set the stage for students’ next steps, specifically the need to know what’s happening at the atomic-molecular scale. Take a moment to show students that you have arrived at the “top of the triangle” on the instructional model. This means they will be making a transition. When they went “up the triangle,” they conducted an investigation and collected evidence based on what they could observe using their own eyes and also tools (e.g., macroscopic observations). Now they are preparing to go “down the triangle,” when they will figure out how to explain what happened in the investigations at an atomic-molecular scale by being provided and practicing with a model for scientifically accurate thinking. 10. Save the Evidence-Based Arguments Tools for later. Display slide 11. Tell students that they will revisit their unanswered questions later in the unit to see which questions they can now answer. 11. Have a discussion to complete the Learning Tracking Tool for this activity. Show slide 12 of the 4.3 Evidence-Based Arguments Tool for Ethanol Burning PPT.
- Have students take out their Learning Tracking Tool for Systems and Scale.
- Have students write the activity name, "Investigating Ethanol Burning" and their role “investigator” in the first column.
- Have a class discussion about what students did during the activity. When you come to consensus as a class, have students record the answer in the second column of the tool.
- Have a class discussion about what students figured out during the activity that will help them in answering the unit driving question. When you come to consensus as a class, have students record the answer in the third column of the tool.
- Have a class discussion about what students are wondering now that will help them move towards answering the unit driving question. Have students record the questions in the fourth column of the tool.
- Have students keep their Learning Tracking Tool for future activities.
- Example Learning Tracking Tool Activity Chunk What Did We Do? What Did We Figure Out? What Are We Asking Now? Investigating Ethanol Burning Investigating Conduct an investigation to explore what happens when ethanol burns and use the Predictions and Planning Tool Ethanol burning lost mass and made the BTB change from blue to yellow. There was evidence of heat and light energy at What happens to the molecules of ethanol as it burns?
