Each group will need a soft drink bottle (with cap) and the other half of its soil sample. Ask students to describe the different components of the soil they investigated during the previous session. Tell them that now they are going to observe the make-up of soil in a different way.
1. Have each group add about 1/2 cup of soil and 1/2 teaspoon of alum to the soft drink bottle, then add water until the bottle is 3/4 full. If students have difficulty pouring soil into the bottle, have them make a paper funnel by rolling a sheet of paper into a cone shape.
2. Direct students to cap the bottles tightly and shake the bottles for about one minute.
3. Next, have students place the bottles in the centers of the groups’ work areas and observe how quickly or slowly the different types of particles settle.
4. When layers are visible at the bottom of the bottle, have students measure and mark the layers and draw their observed results on their student sheets. To facilitate accurate measuring, you may want to instruct students to fold a sheet of paper lengthwise, hold it against the side of the bottle, and mark the boundaries of each layer on the paper.
5. After students have completed their observations, invite the groups to share their observations. Ask, How many different layers did you find? What was on the bottom? What was on the top? The heaviest particles, such as sand and rocks, usually will make up the bottom layer, followed by fine sand and silt. Some clay particles are so tiny that they will remain suspended in the water. Plant and animal material also may remain floating at the top of the water. You also might ask, Of what do you think soil is mostly made?
Keywords: algae | animals | bacteria | earthworms | food | living | minerals | nitrogen | non-living | nutrients | phosphorus | plant growth | plant roots | plants | potassium | soil | ecosystem
- Illustration by M.S. Young © Baylor College of Medicine.
- Moreno, N., and Tharp, B. (2011) The Science of Food Teacher’s Guide. Baylor College of Medicine: Houston. ISBN: 978-1-888997-76-7
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Funded by the following grant(s)
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