Question

highlight the dependent variable (the thing that you observe or record)
homer notices that his shower is covered in a strange green slime. his friend barney tells him that coconut juice will get rid of the green slime. homer decides to check this out by spraying half of the shower with coconut juice. he sprays the other half of the shower with water. after 3 days of “treatment” there is no change in the appearance of the green slime on either side of the shower.

Explanation:

The dependent variable is what's observed/recorded. Here, we observe the appearance of the green slime (whether it changes or not) after the "treatment" (spraying coconut juice or water). So the dependent variable is the appearance of the green slime on the shower.

Answer:

The dependent variable is the appearance of the green slime on the shower (specifically, whether there is a change in the green slime's appearance after 3 days of treatment).