Grade 4 Rocks

Sedimentary Rock Exploration

In this exploration, the students were asked to place particles of different sizes in a jar.  They were asked to shake the jar vigorously and observe which particles settled first, second … last.  

Students observed different things.  Some said that the larger particles, that is, the biggest rocks settled at the bottom of the jar first while the sand and baby powder settled last.  Some observed that the baby powder and sand started settling first because there was so much of it.  

A student suggested that the biggest rocks settled first because of how heavy they are, but then the sand and baby powder was able to settle between the spaces of the rocks.  This is how they ended up underneath the rocks.

The students were then asked to compare this exploration to how sedimentary rocks form in real life.  

 


Weathering and Erosion

The following week, we explored Weathering and Erosion through 3 hands-on activities.  The students gathered materials for a station, followed a scientific procedure, and had a class discussion based on their observations.

Station 1: Physical Weathering

If you apply enough pressure to a rock what do you think will happen?

The rock will crumble and break apart.
 

Why is this an example of weathering?

Just like the sugar cubes crumbled when I shook the bag, so do rocks break apart if there is a lot of rain or wind.

 

Station 2: Water Erosion and Deposition

Which part of this experiment demonstrated erosion?

When the soil and some pebbles washed down the slope, this was erosion.

 

Which part of this experiment demonstrated deposition?

After the soil was washed down, it ended up at the bottom of the container.

What could be done to prevent or slow down the process of erosion?

If you put boulders on the soil or plant trees and crops, this will help to slow down erosion.  They will keep the soil together.

 

Station 3: Wind Erosion

What is happening to the rock?

The rock is getting smaller and smoother as I rub the sandpaper on it.
 

How does this demonstrate wind erosion with sand?

At the beach, wind can pick up sand particles and brush them against the rock.  The sand will eventually wear down the rock.

 

Sabrina Ghany
sghany@isps.edu.tt
Grade 4 Teacher