Oxygen is critical to life. In the worm bin, oxygen is absorbed through the skin of the worms allowing them to survive and plow their way through all the scraps. But oxygen is also critical to the microbes and bacteria that assist the worms in their process. The absence of oxygen serves as a tipping point, transitioning the composting process from aerobic to anaerobic.

When the process tips to anaerobic in the absence of oxygen an alarm goes off, one that our noses detect. That earthy rich soil smell is replaced by the smell of decomposition.

Discuss the role that oxygen plays in the health of the worms and the bacteria that assist them. Worms take oxygen in through their skin but only with proper moisture. Oxygen is required for the bacterial process to remain aerobic.

Reflect on the tests performed in the Beginner Lesson – squeeze test, smell test, moisture test – and discuss the importance of being diligent in monitoring the conditions in the worm bin.