I noticed the official College Board practice exams have questions that feature the "for each" loop. There were at least 3 questions per practice exam, so I figure it's something my students should know. I couldn't find it referenced anywhere in Code Studio, so I tried to make some practice problems - a couple training wheel problems, a couple that I modeled off of the practice exam problems.
Thought I'd share in case you think your students might find these helpful:
Link to homemade "for each" practice problems