Complete instructions for conducting activities in this slide set, including materials needed, setup instructions, student sheets (in English and in Spanish), answer keys and extensions, can be found in The Science of Air Teacher’s Guide, which is available free-of-charge at http://www.bioedonline.org/lessons-and-more/teacher-guides/air/
1. Hold up a piece of bread and ask the students if they know who or what might use it for food. Prompt them to consider all the possibilities. Follow by asking if they ever have seen a rotten apple, moldy slice of bread, etc. Point out that when something is rotting, other living things are using that object for food. Ask, How do you think these living things spread from place to place? Remind the students of the particles they observed in the “Make a Dust Catcher” activity. Mention that some of the tiniest particles in dust are produced by organisms as a means of spreading to other places. Tell students they will be able to observe some living things that spread in this way.
2. Have Materials Managers pick up materials for all members of their groups. Have each student label a container with a piece of tape on which the student has written his/her name.
3. Direct the students to examine their bread samples with a magnifying glass, and draw or describe what they predict will happen to the bread in the first space on the “Bread Mold Observations” sheet. In the second space, have students draw or describe the bread as it appears at the beginning of the investigation.
4. Each student should place the bread in his/her container and add a few drops of water. Store the containers in a dark corner or cupboard.
1. For the next 3–7 days, have students observe their cultures (with and without a hand lens) at one- or two-day intervals. Do not allow students to open the containers in which molds are growing. Some breads may grow mold in as little as 24 hours; others may require seven days or more.
2. Have students record their observations on their data sheets.
1. When all or most cultures (some breads treated with preservatives may not grow mold within the time allotted) have visible molds, instruct students to make their final observations.
2. As a class, decide how many different kinds of molds are present on the bread samples. Have students make a list of the characteristics they use to distinguish one mold from another. Prompt them to think about whether some molds seem to grow on certain types of bread. Ask, How did the mold get to the bread? (Spores were present in the air and landed on the bread.)
3. One fungus that will be present is bread mold. It consists of dark gray threads forming a loose, tangled mat that may reach a centimeter in thickness. Find several samples of bread mold from the class’s cultures, and give a container with bread mold to each group.
4. Have students observe the bread mold inside their containers with their magnifying glasses. They will be able to see the individual threads with small dark dots at the ends. The dots are the spore-producing parts of the fungus. (The actual spores are very tiny.) If you have access to microscopes, place a few strands of the bread mold (using forceps or tweezers) under microscopes for students to observe. Students will be able to see the tubular structure of the filaments (hyphae), the round, dark heads that produce spores and, depending on the magnification, some of the tiny, round spores. Project the “Common Bread Mold” page to help students spot the different parts.
5. Conclude by leading a class discussion of the role of molds in causing indoor air pollution. You may wish to refer to the story, Mr. Slaptail’s Secret, in which Rosie, one of the characters, is allergic to mold spores.
- Illustration © Baylor College of Medicine.
- Moreno, N., Tharp, B., and Dresden, J. (2011) The Science of Air Teacher’s Guide. Baylor College of Medicine: Houston. ISBN: 978-1-888997-74-3
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My Health My World: National Dissemination
Grant Number: 5R25ES009259
The Environment as a Context for Opportunities in Schools
Grant Number: 5R25ES010698, R25ES06932
Foundations for the Future: Capitalizing on Technology to Promote Equity, Access and Quality in Elementary Science Education