STEM Rocks!

Created by

Let's Talk Science National Office

Activity Language

English

Grade

Grades 4-6, Grades 7-8

Time Needed for Activity

Less than 1 hour

Subjects

Chemistry, Earth and Environmental Sciences

Good for Activity Booth

In this workshop for Grades 4-8, participants engage in the process of turning rocks into paint. They will learn how to crush and grind these rocks into fine pigments.

What You Need

Pre-workshop

Rocks (softer is best) and/or clay
5 tbsp powdered gum Arabic
1/8 cup honey
1 cup water
2 glass jars with lids
Storage containers (reused yogurt containers work)
1 fork
Mortar and pestle
Fine sieve (0.2mm or smaller mesh)
PPE (gloves, goggles, mask)

Workshop

2 spoons
Metal palette or putty knife
Glass or marble board
Small containers to store paint (e.g., seashells, acorn
caps, thick paper folded into a box)
Paint brushes
Thick paper to paint on

Guide:

STEM Rocks! - Guide

Safety Notes

For the pre-workshop prep: wear gloves, safety goggles and a mask – be careful not to breath in dust!
Depending on the age, participants can help create the paint. You can allocate some prep time at the beginning of the workshop for this.

What To Do

Pre-workshop

Make paint medium:
- Put gum Arabic and honey in a glass jar that can hold 2 cups.
- Boil the water and add a little to the glass container.
- Mix the ingredients into a paste with a fork.
- Slowly add remaining water while stirring.
- Put lid on the container and refrigerate until use.

*Alternatively, buy prepared watercolour medium from an art supply store.

Grind rocks/clay:
- Wash and dry rocks, and dry clay prior to grinding.
- Break larger rocks up using the pestle.
- Grind rocks/dry clay into a powder using the mortar and pestle.
- Sift the powder, and grind again if needed.
- Store in a container until use.

Activity

Put 1 tbsp of ground rock/clay onto the glass board.
Make a well in the middle of the rock/clay pile, and fill it with paint medium.
Using a palette or putty knife, mix the ingredients.
Using the bottom of a jar, rub the mixture against the board in circular motions until it feels a little thicker, like butter.
Scrape the paint mixture up using a palette or putty knife, and transfer to a small storage container.
Gently dip a wet paintbrush in the paint and you’re ready to draw or write!
Let the rest of the paint mixture dry in its container for long-term storage. When reusing the paint later on, repeat steps 1-6.
Grind rocks/clay of multiple colours to make paints of different colours.

Discovery

By transforming rocks into pigments, participants can understand the properties and composition of minerals. The physical and chemical changes involved in grinding and extracting pigments from rocks also contributes to the understanding of weathering and erosion as part of the rock cycle.

Understanding the rock cycle is important for considering the long-term changes in geological processes due to phenomena such as climate change. Climate change is a change in the statistical distribution of weather when measured over the long-term. These changes, in turn, influence the processes within the rock cycle. For example, an increase in temperatures can increase the physical weathering of rocks, while changing precipitation patterns impact chemical weathering, such as the formation of carbonic acid that can dissolve rock. Weather events made extreme due to climate change contribute to erosion and transport of sediment into water systems. The burning of fossil fuels can release greenhouse gases, such as sulphur dioxide and nitrous oxide into the atmosphere. These gases combine with water and oxygen to form acid rain. These environmental conditions under climate change influence the rate and intensity of the rock cycle's key processes. Recognizing this connection is important for understanding how climate change can shape landscapes and impact the balance of the rock cycle over time.

As humans develop infrastructure and communities around large geological structures, establishing preventative measures to prepare for incoming disasters due to climate change will be important in the future. For example, scientists in California are already considering how increasing the process of rock weathering may provide a natural way to remove carbon dioxide from the atmosphere. This can occur through the chemical reaction of carbonic acid with silicates found in igneous rocks near volcanoes. The increased weathering of these rocks also has been found to increase crop yield, providing a necessary nutrient to plants in soil. Understanding rock chemistry may be a crucial solution to climate change in the future.

Learn more about the effects of climate change on minerals through the Cookie Mining – Climate Edition activity.