Soil science

Armed with our new microscopes, we returned to "the lab" to analyze the soil samples we had collected from our two holes.

To hone their skills, our soil scientists first trained with separated soil components: sand, clay, humus, and gravel. I constructed “slides” from 1-inch by 3-inch pieces of cardstock, each punched with a hole and backed with transparent tape to hold a sprinkle of soil.

The children examined each component with a hand lens and then a microscope, creating a scientific illustration for each.

"I discovered that each soil has a different texture."--CJ, 3rd grade

"I observed that the clay looked like dust."--EN, 3rd grade

"Sand has crystals and grains of rock in many different colors."

"Gravel looks like mountains with snow on it." --KL, 3rd grade "The gravel looked like popcorn."--EN, 3rd grade

“Humus had a big chunk that looked like bark.”

Finally, our soil scientists had the expertise they needed to recognize these soil components in the samples from our holes. They began by examining soil collected from different depths (surface, 8cm deep, 23 cm deep, and 29 cm deep) in the hole near the building.

One group observed, "It looks like there is quartz or calcite in it and clay." Another group noticed a tiny chunk of broken glass. A third group concluded, "We think we would need humus--lots and lots of humus--to make a garden by the building."

The hole we dug in the grassy area produced more interesting finds.
"The hole near the building has more crystals than the one in the grassy area."
What would explain this difference? "The one in the grassy area had more clean water and the non-grassy area gets dirty mop water. Also, the grassy area has humus that has dead things in it that earthworms eat, and earthworms make good soil." Another group warns gardeners, "Make sure not to hurt the living creatures because they help the soil stay moist."

“We found something moving in our soil.”
“Ms. S., you better come and look at this.”
When I went over to check, I had difficulty finding it. “It has crystals and dirt on it.” . . . "Where?” . . . . “It’s the thing that’s moving!”
“Oh! Oh, my!” Suddenly I am a Minnesotan mom. “Oh, my.” Something translucent and invertebrate pulsating in a hole-punch sized soil sample. Pinworm, perhaps? (Based on later research, probably not.) From across the room, a few moments later, another group issued gleeful cries of, “We found a parasite!” Yes, soil is the place where geology meets biology and becomes habitat. Special attention will be given to hand-washing today!



What we're reading:
Kids Discover Soil
Dirt by Steve "The Dirtmeister" Tomecek (National Geographic)

What I’m reading:
Last Child in the Woods by Richard Louv