Norwood Science Center. Geology Grade 4

Transcription

1 Norwood Science Center Geology Grade 4 Background Information: Three things can happen to precipitation that falls on the ground. Some of it may be returned directly to the atmosphere by evaporation. Some of it may form runoff (technically water that returns to the ocean). Most of the time a quantity of water sinks into the ground. Any water that sinks below the surface is called ground water. Water can sink into the soil because there are open spaces between the soil particles. The ground water fills these spaces. The rock below the soil may contain many joints and cracks. Water fills these empty spaces too. Water also enters the rock that seems to be solid. This is because almost all rocks are made up of grains of different minerals. This causes space between the different grains in most solid rock. Water can fill these tiny spaces. These spaces are called pores. The amount of empty space in soil or rock is called porosity. The porosity of some rock is %. This means that onequarter of the rock is empty space! All samples of rock and soil have a certain porosity. The porosity controls how much water rock or soil can hold. Geology Gr 4 Porosity Page 1

2 TITLE: PURPOSE: MATERIALS: POROSITY What type of soil retains the most water? (per three students) One 0-ml beaker of colored water Three 3-oz. paper cups Three 50-ml beakers Three -ml graduated cylinder Newspaper Three porosity worksheets (per teacher) Containers of: Sand Gravel Small spoons (3) Collection bucket PROCEDURE: Advanced preparation: 01. Using the pointed end of a drawing compass, the teacher will pierce five holes in the bottom of each paper cup. Place a paper cup into each of the -ml beakers. Classroom lesson: 01. Review the major aspects of the water cycle (precipitation, evaporation and condensation). Review the action of water once it has landed/melted on the ground (evaporation, runoff, seep into the ground). 03. Inform students that fresh drinking water comes from water that seeps into the ground or runs off the ground into bodies of water. Geology Gr 4 Porosity Page 2

3 04. The ability of the ground to hold water is very important. This is particularly true for someone trying to grow crops or people who are trying to conserve water in times of drought. 05. Group students in teams of threes. 06. Distribute a sheet of newspaper to each group. This will be the work surface for the lesson. 07. Distribute the following equipment to each team and demonstrate how to set up the materials on the newspaper : three -ml graduated cylinders one 0-ml beaker three paper cup/beaker set-ups three porosity worksheets 08. The teacher fills one paper cup with sand to the top. 09. The teacher repeats the procedure with the dirt and gravel samples in the remaining two paper cups. 10. Fill the 0-ml beaker for each group with colored water. 11. One student in the team fills their graduated cylinder with ml of colored water. 12. Instruct that student to slowly pour all ml of water into the paper cup containing the dirt. This pouring process should be conducted in short increments of time thus allowing the water ample time to percolate into the pore spaces between the gravel. 13. The second student is to follow the same procedure for the sand sample. 14. The last member of the team should follow the procedure for the gravel sample. Geology Gr 4 Porosity Page 3

4 15. Once the water has ceased dripping into the beakers, students can visually compare/contrast the three samples regarding their ability to hold water. 16. The teacher will collect all the paper cups in the collection bucket for disposal at a later time. 17. Each student in turn will pour the water from the 50-ml beaker into his/her -ml graduated cylinder. They will then calculate the volume of the water retained by the soil sample [ ] and write the answer on their worksheet sharing that value with the other members of his/her team. 18. Students are to identify the soil type that would be the best protection against drought. Geology Gr 4 Porosity Page 4

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