By now you should know about the 4 main principles of design (aka CRAP or CARP or PARC), Contrast, Repetition, Alignment, and Proximity.
You, being the creative and intelligent individual that you are, can have some freedom in what you design and how you demonstrate those principles. If you have your own ideas or your own projects that you want to design, go for it, so long as you demonstrate all 4 principles and explain how they were used to draw attention toward or away from elements.
If you need a suggestion though, I’ll suggest that you design a poster for an upcoming event. You can use a real event or make one up. You can make it for a sporting event, concert, meeting, bake sale, art showcase, whatever!
You can choose to put this together in InDesign, Illustrator, or Photoshop, so long as it’s 11 inches by 17 inches (The resolution needs to be 300 dpi if you’re in Photoshop)
You need to incorporate images (high quality), some kind of shape(s), and text that is different levels of importance (such as a headline and details.)
Once you’re done, your reflection will consist of explaining how you used the CRAP principles and how they drew attention toward or away from elements in your poster. Explain that clearly in a document and hand it in for your reflection mark.
If you need a review, this is a pretty good one (although there are many on YouTube)