Skip to Content

Decomposers | Pre-Activity 0.1

Pre-Lesson Activity 0.1: Investigation Set Up

Students prepare Petri dishes with bread and water, record initial masses, and let bread mold for 7 days. After about a week, the mold should have grown enough to yield robust data for the investigation in Lesson 3.

Materials You Provide

  • Bread slices (4 per group of students)
  • Digital Balance
  • Labels for Petri dishes
  • Permanent marker (1 per group of 4 students)
  • Petri dishes with 4 lids (4 per group of students)
  • Roll of tape (1 per group or class)
  • Spray bottle with water for misting the bread (1 per class or group or class)

Resources Provided

Setup

Prepare the bread, spray bottles, Petri dishes, labels, digital balances, and markers. Print one copy of Pre 0.1 Bread Mold Investigation Worksheet for each student. Print one copy of the Bread Mold Class Results 11 x 17 Poster, or prepare a computer and projector to display Bread Mold Class Results Spreadsheet.

Directions

1. Introduce the unit to students.

Tell students that in a week from now, they will begin to study how things decay. To prepare for that, they will set up the investigation by putting bread in Petri dishes, recording data, and keeping the bread in a warm, dry place for a week.

Assessment

Use the Bread Mold Class Results 11 x 17 Poster or the Bread Mold Class Results Spreadsheet to evaluate students’ success at measuring mass changes in their bread and Petri dishes. Make sure that students have recorded the weight of their individual Petri dishes and bread as well as their group’s Petri dishes and bread on their worksheet before moving on.

Modifications

Use Tab 3 – Daily Log of the Bread Mold Class Results Spreadsheet to have students keep a daily log of the mass of their Petri dish and bread. This will allow them to observe mass loss each day and may help them identify the pattern of overall mass loss more easily.

Tips

Store the Petri dishes and bread together in a cool, dark place, and make sure they are all labeled before the end of the class.

Extending the Learning

Students may be interested in keeping photo documentation of their moldy bread to accompany the data they collect.