Here's an observation from a newcomer.

This, and the next several lessons, are my favorite so far -- those found most challenging, actually.

I got stuck at the use of the SUM function to tally a "column" of a field on a continuous Form and because I stubbornly worked my way to the solution, I've managed to correct an ignorance I've carried for years.

The function works with this syntax:
   =Sum( <tableFieldName> )
and not,
   =Sum( <formTextBoxName> )

However, because you have the custom of using the same name for both tableFieldName and formTextBoxName (which is something I've never done myself) the proper syntax was somewhat unclear to me as I studied from your lesson video. I'd used my familiar naming convention as I constructed the Form, which resulted in unique names for these elements.

Of course, it can work either way, so long as we follow the code requirement. I thought I'd mention this in case other noobies sprain their ankles on the same stone.