Dirt: you know it, you love it, some of your students are coated in a thin layer of it (or, if you’ve got a Kevin in your class, it’s more of a Pigpen-esque cloud of it). It’s everywhere and nowhere at once, except the “nowhere” part. If you know anything about dirt, or soil if you want to be all fancy-pants about it, you know there are many different types, each with its own properties and compositional makeup. How do their different makeups relate to density and sedimentation? This Demo Science science demo will help your students understand a bit more about dirt.
Get Your Hands Dirty
For this earthy experiment you’ll need roughly half a cup of as many different types of dirt that you can reasonably find (shoot for at least topsoil, upper soil, subsoil, and deeper soil), water, a roll of masking tape, a marker, and an equal number of jars as you have soil samples. Jars are the only container option here, as all the dirt bags have been summoned to Washington for Cabinet positions.
First, put each dirt sample into its own jar, then use your tape and marker to label each jar with what type of soil it contains. Add water until the jars are each roughly three-quarters full. Then put the lids on and secure them tightly—you don’t need to spike ‘em closed with pneumatic rivet nut tools, but still, the tighter the better…
…because next your volunteers will be shaking the bejesus out of the jars. (Oh yeah, you’ll need to round up some volunteers, one for each jar.) When your students have thoroughly shaken their water and dirt mixtures, set the jars aside so the contents can settle. The settling may take a while, so maybe do this first part at the end of one day’s class and pick up from there at the beginning of the next day’s class.
When the jars are all Steve Guttensettled, have your students observe each soil sample and make labeled illustrations of what they see. What do they see?
Dirt Science Is Still Science, Bro
If everything went according to plan, the soil samples will have formed bands/layers of their mineral components. In most cases, there will be large, heavy, dense particles in the lower layers, with each successive layer getting progressive lighter in both weight and color. The lightest bits will, therefore, be at the top. By studying these layers, you can determine the composition of your various soils.