Activity 4.1 - Predictions about Ethanol Burning (30 min)

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 1.2 Expressing Ideas 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 11x17 Poster (1 per class)
Three Questions Handout (Color Version)
Three Questions Handout (BW Version)
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 11x17 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 and Planning about Ethanol Burning PPT.

2. Revisit students’ ideas from Activity 1.2.

Display slide 3 the 4.1 Predictions and Planning about Ethanol Burning PPT.

Remind students of the ideas and questions they had in Activity 1.2.
Return students’ completed 1.2 Expressing Ideas and Questions Tool for Ethanol Burning and ask them to review their ideas from the first lesson.
You may have typed and saved students’ ideas and questions on the 1.2 Expressing Ideas and Questions about Ethanol Burning PPT. Or you may have taken a picture of students’ sticky notes. Display the visual and review what students shared.
Tell students that in this lesson, they will be investigating what happens when ethanol burns to learn more about what happens to matter and energy during chemical changes.

3. Have students read the Good Explanations of Chemical Change Reading

Show slide 4 of the 4.1 Predictions and Planning about Ethanol Burning PPT. Give each student a copy of 4.1 Good Explanations of Chemical Change Reading and a copy of the Three Questions Handout (or have them take out their existing copies). Have students read 4.1 Good Explanations of Chemical Change Reading using the Questions, Connections, Questions Student Reading Strategy. See the Questions, Connections, Questions Reading Strategy Educator Resource document for information about how to engage students with this strategy. After the students read, ask them to define combustion in their own words. Place a copy of the Three Questions 11x17 Poster on the wall for reference if it is not there already.

As students read each section, have them stop and highlight or underline the following rules about matter and energy on their handout.
Atoms are bonded together in molecules.
Atoms last forever.
Energy lasts forever, and energy can be transformed.

4. Watch the first half of the Burning Ethanol Video.

Display slide 5 of the PPT.

Watch the Burning Ethanol Video until the first intermission where Darryl and Nina ask the students to make predictions about what happens when ethanol burns.
Pause the video at 03:10 to discuss the questions posed on the screen before students complete the predictions and planning tool.

5. Have students complete Part A of the Predictions and Planning Tool for Ethanol Burning.

Show slide 6 of the PPT. Pass out one copy of 4.1 Predictions and Planning Tool for Ethanol Burning to each student and ask them to record their ideas as individuals for what happens when ethanol burns under part A.

Remind students that these are just predictions, and that there are no wrong answers at this point. Encourage them to write down all of their ideas on the tool.

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 yellow to blue, then a chemical change may be using CO₂ as a reactant.
If the BTB changes from blue to yellow, then a chemical change may be producing CO₂

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 both the matter movement, matter change, and energy change questions.

9. 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

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 4.2
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 Investigation 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 11x17 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: When students see gas bubbles leaving the soda water, do they cite that as evidence that atoms are leaving the soda water? Do they suggest ideas about what gas might be in the bubbles? Note whether students connect bubbles leaving soda water with atoms leaving soda water.

During the class, listen to the ideas 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.