In this Earth Science lab, students determine which type of soil they have in a sample found from my garden. On day one students place soil in a graduated cylinder, filling it to about 25 percent. They then fill their cylinder up 3 times that amount or nearly full with a soapy water solution. If students don't put enough of the soapy solution in, their soil turns to a thick mud and can't separate and settle well to the bottom. To create the soapy solution, all I did was add a dry borax type soap to distilled water. You don't want to use soap that is sudsy, because as they shake the cylinder, it really suds up. I know from experience. The purpose of the soap is to help break bonds holding dirt clumps together. Have the students tape the top of the cylinder extremely well, so that they don't get mud all over their hands or your desks. I have tried using rubber stoppers before, but students found a way to get those stoppers jammed and stuck in the cylinders, so this year I us
In this Earth Science lab, I first discuss with students what soil permeability and porosity is and why that matter. The more permeable a soil is the easier the soil drains water. Some plants prefer water to be drained quickly. Soil porosity is how much space is in between the different sediments. A good way to see if soil is porous or not is to see how much water it can soak up or hold onto. Some plant prefer water that can hold onto water so that they constantly can use it.
Before beginning this lab, I announce a good week in advance that I will need copper pennies dated 1982 or older. I also give them 1 extra credit point per penny that they can donate to science. I did learn however after my first year, that you need to cap it. Otherwise you have those students who can raise their grade significantly after bringing in 100. I did not expect that the first time I did this. I now cap it at 5 per student. This also spread the points around.
The reason you need copper pennies 1982 or older is because you are looking for pennies with a high concentration of copper in them. After 1982 pennies were mostly zinc and very little copper in them. If you don't personally verify the dates though, some newer pennies will sneak in.
In this lab students will need to have access to a computer that can run "Flash" and the Phet Density Lab worksheet. The worksheet is designed to be pretty self explanatory. I am looking for students abilities to follow written instructions and ability to collaborate with a partner. By the time students get their machines, log on, Google Phet Density, and complete the task it took about 45 minutes for my smaller classes and 50 minutes for the larger ones. This allowed the rest of the time period to discuss key concepts that are explained below.
During the third day of Earth Science class, we discussed the scientific method. I share personal stories of when I fix computers and how I use the scientific method to do so. I start off by talking about clients bringing me a computer that turns on but won't display anything.