Activity 4.2 - Observing Ethanol Burning (30 min)

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 CO₂ 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 (or spreadsheet) (1 per class)
4.2 Observing Ethanol Burning Worksheet (1 per student)
4.2 Grading the Observing Ethanol Burning Worksheet (1 per group)
4.2 Observing Ethanol Burning PPT (1 per class)

Recurring Resources

(Optional) BTB Color Handout
(Optional) BTB Information and Instructions Handout
Three Questions Handout (Color Version)
Three Questions Handout (BW Version)
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 print copies of the BTB Information and Instructions Handout for each group, or print a few color copies of the BTB Color Handout for students.

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.
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.

7. Have students record data and observations.

Display slide 8 of the PPT. Have students record their group’s data and observations about the mass change and BTB color on their worksheet.

Next, have students select a recorder to input their group’s results on the 4.2 Ethanol Burning Class Results 11 x 17 Poster, or in the 4.2 Ethanol Burning Class Results Spreadsheet

8. Have students’ groups compare and identify patterns in BTB Color.

Display slide 9 of the PPT

Lead a discussion to help students compare results across groups and identify patterns in the data. Have students discuss how BTB has a gradient of colors depending on how much CO₂ is absorbed.
Optionally, give each group or pair of students BTB Color Handout to use as a reference guide.

9. Have students’ groups discuss patterns in class results.

Show students slide 10 to discuss patterns that students see in the class results.

Ask students to identify patterns in the data for both the mass change and also the BTB color change, and discuss any outliers or unexplained data points.
If you input data into the spreadsheet, the software will construct a graph of the students’ data. Use the graph to elicit more interpretation of their observations.

10. Watch the end of the Burning Ethanol Video.

Show slide 11 of the PPT

Have students watch the Burning Ethanol Video starting from 3:10 to observe Darryl and Nina’s results to the burning ethanol investigation. Ask the class to compare their own results to Darryl and Nina’s results, pausing the video when the data are shown.

11. Have students compare their class’s data with data from another class.

Show slide 12 of the PPT to view data from Ms. Angle’s class.

Ask students to compare the patterns they observed with the patterns from Ms. Angle’s class. What similarities or differences do they notice? What patterns do they see?

The remainder of the unit is based on the assumption that your class results are similar to those of Ms. Angle’s class and the Ethanol Burning video. If your class results are significantly different for any reason, after a conversation about why that may have happened, decide whether to have students conduct the investigation again or to refer to Ms. Angle’s data as they work through the remainder of the unit.

12. Have students compare their class’s BTB color with data from another class.

Show slide 13 of the PPT to view BTB from Ms. Angle’s class.

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 Questions 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.