Soil color is often an indication of the presence of iron (Fe) oxides or organic matter on soil particles, not the soil itself. The minerals beneath are often quartz or feldspar, which are grey. In saturated soil (wet), Fe3+ is reduced to Fe2+ due to a microbial mediated redux reaction. If all the oxygen is removed from the soil/water (by the microbes), the soil becomes anaerobic. The red color of the iron oxides is removed in the reaction and the soil becomes grey. Soil scientists can identify where the water table is even when the soil is not saturated. The presence of grey colors indicate height of the water table. In this activity students will compare jars of different colored soil that are wet to observe the anaerobic reduction of the iron compounds in the soil (the color fades to grey). This is compared with a jar of sterilized wet soil. Teachers will need to procure soil samples for the students in advance of the lesson.