So, dirt, right? Earth is literally full of the stuff. Kevin is covered in it. It comes in many forms, some of which are quite useful if you know what you’re doing with ‘em. I’m talkin’ everything from potting soil to clay here—“dirt” is a wide-ranging term, in my book. No matter what kind of dirt you’re dealing with, they all have one thing in common: air. As in, there’s air in there somewhere, no matter what, but in wildly varying amounts.
This handy dandy Demo Science experiment will help your students see how different types of dirt are affected by the amount of air present in them. To the scienceatorium!
Dirt Don’t Hurt
For this one, all you’ll need are a variety of different soil samples, several small, clear glass jars (the same number of jars as you have soil samples), and some water. Easy peasy lemon squeezy.
Round up a few volunteers—one student per soil sample works well—and give them each one jar and one pile of dirt. (Or one of however you’ve organized your dirt. One bucket of dirt, maybe? I don’t know, I can’t hold your hand through this whole thing, man.) Have each kid fill his or her jar about half full with their respective dirt. Then, have them pour in water until the jar is nearly full.
Have all your students observe what happens next. Depending on the individual soil sample being tested, there will be varying amounts of air bubbles, um, bubbling up from the soil to the water’s surface. What do the air bubbles tell us about the dirt in the jar?
Life’s A Garden: Dig It
The more bubbles a given soil sample produces, the larger the amount of air trapped in the spaces betwixt the dirt particles. Densely packed dirts, like clay, have far less room in them for trapped air. Looser soils tend to have plentiful space for air pockets.
This type of dirt also tends to be more nutrient-rich, and is therefore far better for growing plants in. Is there a correlation there? Yes, yes there is. But that’s an experiment for another time.