Soil Investigation

What is soil made of and why is it important to plants? Investigate the composition of soil by using your senses and simple tools to make inferences about why soil is important for plant growth. 

Materials 

• Soil with visible component parts (mulch, minerals, etc.)  

• Paper and a writing utensil (optional) 

• Magnifying glass (optional) 

• Stick or small shovel (optional) 

• Access to a garden (or similar space) (optional) 

Observation Ideas 

• Using a stick, small shovel, or your hands, dig up a small sample of soil. With the naked eye, observe the color and particle size of the soil.  

• Using a magnifying glass, engage in close looking to make observations about the different materials soil is made of, including organic materials like dead leaves, sand, silt, clay, and air. You might even spot something alive and moving around, like a pill bug or a worm! 

Discussion Ideas 

• Before you dig, what do you predict you will find when you look at the soil? Why do you think that? Was your prediction correct? Why or why not? 

• What does the soil feel like? Use your hands to feel the soil and make observations about its texture (e.g., gritty, rough, soft), moisture (wet or dry), and density (e.g., light, heavy, loose, packed). 

• What do the different parts of the soil remind you of? What path might the different parts have taken to become the soil? 

• What do you wonder about soil? Talk in pairs or small groups about what you have learned about soil and discuss the questions you now have. Can you answer your peers’ questions based upon what you have learned through your investigations? How might you plan an investigation to answer your questions? 

Further Investigation Ideas 

• Does soil look different in different gardens? How might soil be different from compost? Make predictions, develop an investigation to test your predictions, record your data, and share what you learned. 

• Use a moisture meter to determine how much water the plants in a garden are getting. Repeat in different spots around the garden. Compare the data from each location. Are the numbers the same in all locations or are they different? If they are different, calculate the average of the numbers. Record your information. Why might knowing the soil moisture on the same day from one year to the next be useful?