Hey @lisa_reed just wanted to follow up quickly but @mike is absolutely right. Especially early in the life of a course we pilot and update a course frequently in response to feedback. Units 2 and 3 just went through substantial edits that should significantly improve your experience this summer. You can read a little more about them at code.org/educate/csd/old.
We don't anticipate making significant changes to Units 2 or 3 between now and the summer, but we may make smaller tweaks at the lesson level in response to feedback. We will be making similar updates to the rest of the course but those likely will not happen until after your summer class has wrapped. Even 2 and 3 will likely eventually see changes as we scale up from a small pilot to thousands of teachers running this class. If you want to know what we're up to you can sign up for the monthly email on on this form.
Hope that helps. Finally I can't help but make a quick plug for trying some of Unit 1. We've had very positive feedback on the unit from piloters and starting with it is our suggested implementation. Obviously everything we publish you are free to use as choose, however, and we'd love to hear from you back on the forums once you're into the course.
Cheers and good luck this summer!