Students look closely at the different sized components of each soil type (if the soil sieving activity is done previously, the students have separated the soil into different-sized components).
Working in their group, students record on their worksheets what components they find for each soil. (see attached files for worksheets for different ages).
Optional: to help the students look more closely at the components, they can draw one or two of them.

Group by group, students report to the class what they find in their soil samples and add to a class chart.
For older students, for each component, decide as a class whether is is organic matter (from a living thing) or inorganic/mineral matter (from rock), then add it to a class chart.
See the "soil components results" attachment for an example of what a class found.

Discuss the relative amounts of organic and inorganic/mineral material in the different soil types.
For our soil types, forest soil is almost all organic; beach soil is a mix of organic and inorganic although by volume the inorganic component is larger. Fill from city soil was almost all inorganic.
Other classes that get soil from other locations will get different results. See the "soil components results" attachment for one class' results.

Discuss how each soil type was formed and how this determines its’ composition:
The forest soil is mostly made from the decomposition of dead plants by the decomposers (snails, worms, wood bugs). If relevant, refer back to a forest walk and the decomposers observed.
The beach soil is mostly composed of the sand. This is made by the weathering of rocks, and is then carried by ocean currents before being deposited on the beach. The few plants that grow in the sand generate a thin soil as they die and decompose.
The construction site fill is from the layers of soil below the organic layers, so it comes from the weathering of rocks to make particles of different sizes.