Life Cycle - Organisms (6B)
Pre Lab

  • Exploring how food gets rotten.
  • Discovering how mold occurs.
  • mold
  • rot
  • spore
  • Lots of Rot by V. Cobb (Harper)
  • worksheet of rot

Students observe a rotten orange.


How many times have you looked for an orange to eat and found that the last one left had grown soft, blue-green fuzz? Have you ever left a wet towel at the bottom of your clothes hamper and at the time of washing you found that it had green "freckles" all over it? Or how many times have you found bread that has gone stale and has grown black "whiskers?" The green fuzz on the orange, the green freckles on the towel and the black whiskers on the bread are all known as molds. Molds are really tiny fungi belonging to one of the 5 kingdoms. "Molds" are a term that is not really a natural grouping, but until scientists figure out exactly where they belong, we will consider them fungi. Molds are so tiny that we cannot see them unless there are many of them bunched together. To see just one mold you need a microscope. There are many kinds of molds. One of the most common molds is the one which turns oranges into green fuzzy balls. It is called penicillium. This is where the drug penicillin comes from.

Plants use sunlight to make food in their leaves. The green coloring matter acts as a kind of food factory. Molds have no food factories, so they take the food they need from their host. All molds are food robbers.

Foods will eventually rot if not kept cool or not eaten within a certain time unless frozen. The more time food stays around the more of a chance spores from a mold have of landing on it and growing. A spore is the reproductive part of the fungi.

Wherever there is food, air, and moisture, some mold spores will find their way there to settle and begin to grow. If a spore doesn't find the food, air or moisture it needs to grow it does not die. It just waits. It can remain alive for years in its case, waiting for the right conditions to burst open and grow.

  1. Review with students the different kingdoms and their characteristics. You may want to review some of the lower grade material if your students have not developed a feeling for the diversity of life. In this unit, students will look at organisms that they see, but rarely think about as being living.
  2. In a large zip lock bag, place a fresh orange and a "molded" orange and then seal the bag. In another bag, place another molded orange and seal the bag. Place a fresh orange besides the bag with only the molded orange. Place both sets in separate dark, warm areas in the room. Have students predict which will grow mold first. You may want to put other materials next to the bags and observe what happens. For example can plastic become infected or can different types of bread get moldy faster than others?
  3. Use the worksheet for students to identify the types of rot they discovered.. Lots of Rot can also help students identify what they have found.

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