1. Decomposers Unit Activity 3.2 Observing Bread Molding
Carbon: Transformations in Matter and Energy
Environmental Literacy Project Michigan State University
Decomposers Unit Activity 3.2 Observing Bread Molding
Image Credit: Craig Douglas, Michigan State University

2. Unit map
You are here
(Day 1) Use the instructional model to show students where they are in the course of the unit.
Show slide 2 of the 3.2 Observing Bread Molding PPT.

3. Investigation set up from Pre-Lesson
(Day 1) Remind students of the investigation set up the conducted in the Pre-Lesson. 
Display slide 3 of the 3.2 Observing Bread Molding PPT.
Pass out each student’s copy of the Pre 0.1 Bread Molding Investigation Set Up Worksheet. Use the worksheets and the class results (either in poster or spreadsheet form) to review the initial data collected during the Pre-Lesson. Tell students that today they will pick up with the investigation where they left off after the Pre-Lesson.

4. Investigation tools What mass changes will we observe?
What changes in BTB will we observe?
Image Credit: FableVision 
(Day 1) Have students rejoin their Pre-Lesson groups.
Display slide 4 of the 3.2 Observing Bread Molding PPT. Divide students into their groups of four from the pre-lesson.
Pass out one copy of 3.2 Observing Bread Molding Worksheet to each student.
Walk through the steps in Part A of the worksheet that overview how to find the mass of their Petri dish, bread, and mold, and where to record the information. 2

5. Day 1 Instructions (Day 1) Find the Mass of Your Bread and Mold.
☐ Collect your labeled Petri dish with bread and mold, a digital balance, and your worksheet from the Pre-Lesson.
☐ Look on your worksheet from your Pre-Lesson and find the beginning mass of your Petri dish and bread from 7 days ago. Write the mass on your 2.2 Observing Bread Molding Worksheet in the table where it says “Mass of Petri dish and bread and mold before (7 days ago).”
☐ Turn on your digital scale until it reads 0.00g. Place the entire Petri dish with the lid onto the scale. Record the final mass of your Petri dish where it says “End Mass (after 7 days)” in the table below. Note: DO NOT open the lid—classmates may have allergies to bread mold.
☐ Record the final mass of your Petri dish, bread, and mold on your 2.2 Observing Bread Molding Worksheet in the table where it says “Mass of Petri dish and bread and mold after (today).”
(Day 1) Set up the BTB Investigation.
☐ Gather a large, sealable container (1 per group).
☐ Stack all four of your group’s Petri dishes in the container.
☐ Put an open Petri dish with BTB in it next to the moldy bread inside the container.
☐ Record the color of the BTB on your 2.2 Observing Bread Molding Worksheet in the table where it says “Color of BTB before.”
☐ Seal the container and wait 24 hours for results.
(Day 1) Have students read through instructions.
Display slide 5 on the 3.2 Observing Bread Molding PPT.
Go through the steps to make sure that all the students understand what they are doing and why.

6. Let’s do the investigation!
What mass changes do you observe?
What changes in BTB do you observe?
Image Credit: FableVision
(Day 1) Have students record initial data on bread molding.
Display slide 6 of the 3.2 Observing Bread Molding PPT Have students work in groups of four to set up their investigations.
Have students 1) either follow the procedures that they developed themselves in the previous activity, or 2) follow the procedure in the 3.2 Observing Mealworms Eating Worksheet.

7. Possible BTB colors 3 Image Credit: FableVision
(Day 1) Have students review the BTB range.
Show slide 7 of the 3.2 Observing Bread Molding PPT.
Review the colors on the PPT to remind students of the range of bromothymol blue (BTB) colors.
Alternatively, give each group a copy of the BTB Color Handout. 3

8. Before you leave, Day 1 Leave bread overnight in sealed container
Record mass of Petri Dishes
Record color of BTB
(Day 1) Check that students have recorded their data, and wait 24 hours for results.
Show slide 8 of the 3.2 Observing Bread Molding PPT.
Before leaving the bread and mold with BTB overnight, make sure that the students have recorded the mass of their Petri dishes and color of the BTB on their worksheets.
When this is done, leave the bread overnight in sealed containers.

9. Collect data, Day 2
Collect data and record your observations on Part C of the 2.2 Observing Bread Molding Worksheet
(Day 2) Have students record data and observations after 24 hours.
Show slide 9 of the 3.2 Observing Bread Molding PPT.
Have students collect data record their observations by following the instructions in Part C of their 3.2 Observing Bread Molding Worksheets.
Remind students of the range of BTB colors. Alternatively, give each group a copy of the BTB Color Handout to interpret the change in color.

10. Bread mold class results
Group
Starting Group mass (Day 1)
Ending Group mass (Day 2)
Change in mass
Start time
End time
BTB before
BTB after
Notes 1 2 3 4 5 6
Average
Have students organize data using their spreadsheets or poster.
Show slide 10 of the 3.2 Observing Bread Molding PPT.
Have students input their individual and group results for both mass and color change on the Bread Mold Class Results 11 x 17 Poster, or in the Bread Mold Class Results Spreadsheet.
Spreadsheet instructions:
Have individual students report or enter the end mass of each Petri dish into Tab 1 – Individual Data. The spreadsheet will automatically calculate the mass change for each student’s Petri dish in the yellow column.
Click to Tab 2 – Group Data and Averages. Have each group enter their beginning and end colors of BTB from their 24 hour investigation.
Tab 4 contains sample data in the case that you would like to use that instead.
Poster Instructions:
Have individual students add up the end mass of the petri dishes and bread for their group and enter this information into the poster.
Have each group calculate the total change in mass for their group and record this information on the poster.
Have each group enter their beginning and end colors of BTB from their 24 hour investigation.

11. Comparing group results
Results for mass changes
What patterns are there in measurements made by all the groups?
Do the patterns match your predictions?
Results for BTB changes
What patterns are there in observations made by all the groups?
Do the patterns match your predictions?
Lead a discussion to help students compare results across groups and identify patterns in the data.
Show slide 11 of the 3.2 Observing Bread Molding PPT.
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.
Note: If you input data into the spreadsheet, the software will construct a graph of the students’ data. You can use the graph to elicit more interpretation of their observations. 4

12. Bread molding video
Watch the end of the Carbon TIME Bread Molding Video.
Show slide 12 of the 3.2 Observing Bread Molding PPT.
Have students watch the Bread Molding Video starting from where Darryl and Nina show their results to the investigation. Ask the class to compare their own results to Darryl and Nina’s results, pausing the video when the data are shown.

13. BTB results for Ms. Drayton’s class
Day 1
Day 2
start BTB color
end BTB color
blue
yellow
How do your results compare with the results from Ms. Drayton’s Class?
Image Credit: Michigan State University 
Have students compare their class’s data with data from another class.
Show slide 13 of the 3.2 Observing Bread Molding PPT.
Ask students to compare their results to Ms. Drayton’s class results.
Ask students if they recognize similar patterns from their own data. Use the poster or spreadsheet to compare. Ask students if they see the same patterns. What similarities or differences do they notice? What patterns do they see? 5

14. Mass results for Ms. Drayton’s class
Initial mass bread and mold in Petri dish (g)
Final mass after 7 days (g)
Change in mass after 1 week (g)
39.50
37.60
-1.90
23.51
20.75
-2.76
35.57
31.38
-4.19
29.26
25.38
-3.88
31.67
30.37
-1.30
32.18
31.36
-0.82
33.27
31.13
-2.14
30.86
28.95
-1.91
Average change in weight =
Have students compare their class’s data for mass results with data from another class.
Show slide 14 of the 3.2 Observing Bread Molding PPT.
Ask students to compare their results to Ms. Drayton’s class results.
Ask students if they recognize similar patterns from their own data. Use the poster or spreadsheet to compare. Ask students if they see the same patterns. What similarities or differences do they notice? What patterns do they see?
How do your results compare with Ms. Drayton’s class results? 6

15. Complete Part E of the worksheet
Compare your observations with other groups.
Describe any patterns you see in the data on Part E of the 2.2 Observing Bread Molding Worksheet
Have students complete Part E of their worksheet.
Show slide 15 of the 3.2 Observing Bread Molding PPT. Direct students to Part E of their worksheet to describe the patterns they observed during the observation.
Help students to recognize that while the mass changes provide them with good evidence to answer the Matter Movement Question, the BTB evidence provides only a partial answer to the Matter Change Question.
Tell students that it shows that carbon ends up in CO2 in the air, but not where the carbon came from.

16. Revisit your predictions
Which predictions were correct?
Which predictions were incorrect?
What did we see? What does it mean?
What questions do you still need to answer?
Revisit predictions from the previous activity.
Display slide 16 of the 3.2 Observing Bread Molding PPT.
Ask students to retrieve their completed tools from the previous activity: 3.1 Predictions Tool for Bread Molding.
Have them compare the predictions they made with the results of the investigation.
Which predictions were correct? Which predictions were incorrect? What questions do they still need to answer?
Remind students that absorbing food is necessary for decomposers to be able to grow, and to be able to use energy for things like moving. Tell students that they will use the data that they collected here to help them to be able to explain two processes that relate to how things decay: decomposers growing and decomposers moving and functioning.