Promt user for input, then use that information to obtain/display an average number?

Hi I'm wondering if the following is possible in excel:

I'm trying to simplify an evaluation summary worksheet, whereby I would enter all of the scores a certain instructor has received, and then Excel would display average on my worksheet.

So, if I have a category "the goals/objectives of this session were clear", I want to be able to click on cell E2, and when I do, an input box should be displayed, allowing me to enter values 1-4, that this category received (for e.g. 3, 4, 4, 4, 3, 3, 4). Then, Excel should calculate the average on back-end, and in the field should be displayed only the average of those number.

Is this possible? Did I explain it well? Thanks!

M.S.