I have to admit I failed the challenge from Procedural Brick - Random Row Height. To my defense I misunderstood the task. Somehow I was working on varying the brick height in a different way. Right now each brick has a size of 3x1 and I thought we should change it to 3x(random in range) 
Anyways, Stephen was curious about how many managed the challenge so I thought I should tell. I did understand the lecture though, so atleast I got this going for me!
Hey, sorry for the late (very late!!) reply.
Sometimes the challenges end up being spur-of-the-moment " I wonder if the students can do this next bit…" kinda things!
Due to that, sometimes they end up being really easy or really hard, definately don’t worry if you miss out on a challenge. It can be hard to put myself in the shoes of a student sometimes and occasionally the challenges are challenging, which I suppose is the point!
If you miss one, take a few minutes, jump back a bit and try it again on your own after getting a little hint.