Have students read the entire lab and discuss the following:
- Discuss the meaning of permeable.
- Discuss the importance of the size and number of holes poked in the bottom of the cups
- Discuss the effect of the filter paper on the data.
Materials and Preparation
- 3 paper cups
- 3 pieces of paper filter or coffee filters
- one sample each of sand, soil, and gravel
- metric ruler
- measuring cup
- clock or watch
- 3 small blocks of wood
- shallow dish or saucer
- copy of the Permeability Data table
Using your pencil point, make eight small holes in the bottom of each cup. Label the cups sand, soil, and gravel. Cut circles from the filter paper to fit into the bottom of each cup.
- Mark a line 5 cm up from the bottom of each cup. Fill each cup to this line with sand, soil, or gravel, depending on the labels on the cups.
- Set the sand-filled cup in the dish, resting on top of the blocks. Arrange the blocks so that they do not block the holes on the bottom of the cup.
- Measure out 100 mL of water. Start timing as you pour the water into the cup. Finish timing when no more water drains from the cup. Record the time on your data chart.
- Pour the water from the shallow dish into your measuring cup. Record this amount in the data table.
- Repeat steps 2, 3, and 4 with the other two cups.
- Calculate the drainage of each soil type. Divide the amount of water that drained into the saucer by the time it too to drain. Record this rate in the data table. (Rates will vary, be sure the calculated rate agrees with the time and volume data.)
- Which sample had the highest drainage rate? Which sample had the lowest drainage rate? (The gravel should highest drainage rate, while the soil should have the lowest.)
- List the samples in order of particle size, from largest to smallest. (gravel, soil, sand)
- If a sample with the highest drainage rate is most permeable, list the sample from more permeable to least permeable. (gravel, soil, sand)
Write a short paragraph explaining how particle size can effect permeability.
For an extension project, propose a hypothesis to show how permeability might be affected if the samples were mixed together. Test the hypothesis.