Lol! Wow. Isn't it crazy, the things that they find interesting to dispute? There are a couple of options that I can think of: 1) I just plain miscounted and there really are three significant feasts, or 2) There are three feasts but only two of them (the latter two) are significant (i.e. the first one is just kind of in there and nothing important happens, so it doesn't really count as a key EVENT in the plot).
If it's #1, then I apologize and I'd love to know why the kids think the first feast is significant so that I can fix the class plan. If it's #2 (which is the most likely one, to my mind), then you might just point out to the kids that not all events in a plot are equally significant and maybe we'll add a footnote to the class plan. :-)
Let me know if this helps at all or if you have any more feedback! Thank you for bringing the observation---it's always SO helpful to receive corrections!