You can only loop over a list, so only variables that are lists will appear as options. You can select multiple variables to loop over in one Loop module. Looping over a list will perform the same operations on each value in the list.
Start at index:
Define what index of the list you want to start iterating on.
*Note: Indexes in a list start at 0, so the first item in a list is at index 0. Maximum Number of Times to Loop:
Define the number of values you want to iterate over in your list
The Loop module will iterate over each value in the Test Scores variable and print each value to the log using the Print To Log module.