Name of activity:
Hard or Soft Soil Determines Compactness!
Activity written by:
Santa Fe Elementary teachers in a Math and Science in the Outdoor Classroom
Ice pick (or suitable substitute that will stick into the ground), ruler, one
tin can with two open ends, water and container for water, measuring cup,
stopwatch (or watch with second hand), papers, pencils, clipboards
How will the compactness of soil change show how much material can be
absorbed? What will change the compactness of soil? How many levels of
compactness do you think there are around the school and why?
Go to Test Site #1 (an area with very compacted soil)
Drop the ice pick into the soil (from the same level each time). When you
remove the ice pick, keep your finger at "dirt level" and measure
from finger to
end of ice pick how far down it went.
Repeat two more times to get an average depth and to check your
measurements, record in a journal. Ask why didn't the ice pick go in more
or less than it did? (Amount of air space in the soil.)
Push and twist a two side opened can into earth (and push dirt around the
outside of it to prevent leakage).
Take out stop watch and be ready to record the time. Pour 1/2 cup of water
into the can.
How much time does it take for all of the water to be absorbed, record in a
journal. Ask what would cause the water to be absorbed faster or slower?
(Amount of air space in soil.)
Discuss the meaning of compactness (pressed together) and ask what might
be the cause (foot traffic, etc.).
Go to Test Site #2 (an area with less compacted soil, e.g. a garden)
After finishing the procedures at Site 2, ask "Describe how this soil is
different than the soil we tested before.Why did the ice pick go further into
the ground? Why was the water absorbed more quickly?"
If time allows, students could pick a third site and predict what will happen
Students will name different areas of the school ground and predict what
soils will be the most and least likely to compact and why? Where will the
soil be the hardest? Where will it not be very compact?