- Earthworms create tunnels in soil
- Tunnels in soil loosen that soil
- Therefore, earthworms can loosen the soil

- Earthworms can loosen the soil
- The looseness of soil increases the ability of water to enter the soil
- The looseness of soil increases the amount of oxygen in that soil
- Hence, earthworms can help increase the amount of water and oxygen in the soil

So, earthworms can help increase the amount of water and oxygen in the soil
Question
Michelle is interested in improving the quality of the soil in her yard. She wants more water and air to penetrate the soil. What should she add to the soil to help her achieve this goal?

Context
- The looseness of soil increases the ability of water to enter the soil 
- Earthworms create tunnels in soil 
- Tunnels in soil loosen that soil 
- The looseness of soil increases the amount of oxygen in that soil