Not Katie here, but I’ll give this a stab and she can always add .
There are three lessons that are more practice/application, and while they are important and purposeful, they don’t “cover” new stuff, so I would skip those (Lessons 14, 17, 18) if your priority is “coverage”. (Sorry if I’m breaking any hearts with that statement.)
Loops and arrays are definitely on the exam, as well as the concept of simulations, thus 11, 12, and 13 are in. Functions with return values are also in (16), particularly the idea that the computer exits the function once a value is returned (and I believe the curriculum does a good job drawing students’ attention to this in a couple bubbles). The exam does use a slightly different loop - it uses a “repeat until _” instead of a “while” loop in the curriculum. The difference shouldn’t be a big barrier - better to learn the “while” conditional loops from the curriculum than to not learn conditional loops at all.
I would say the idea of processing arrays is important, which is what lesson 15 addresses, but the practice exams seem to process arrays using a “for each” loop, which I didn’t find in the code.org curriculum. There are some questions featuring “for each” in both practice exams (at least 3 questions per exam).
My ideas of what will or won’t be on the exam are based solely on what I’ve seen in the two College Board practice exams - 2016 and 2018, both accessible in your AP Audit account (in the “Secure Documents” section). Thus, take with a grain of salt.
Oh - Definitely do the last lesson - AP Pseudocode Practice Questions - since that lesson specifically targets the programming questions on the exam. I should have led with that one - probably the most exam-targeted lesson in the unit.