Most organelles are far too small and colorless to see with student microscopes and they’re very difficult to study even with professional equipment. As a practical matter, high school students can’t do many direct experiments with organelles. However, it is important for them to have a solid understanding of the structure and function of the more well-known organelles. I usually approach this topic with a modelling activity.
Building models of cells is truly a classic activity. The less common twist I add to the project is that students must present their models to the class when they are done. Specifically, each group must tell the class how they represented each organelle and how their representation suggests the function. I give the first groups to present relatively simple, concrete questions structure and function. Later groups get more detailed and difficult questions since they have the advantage of having heard the presentations of the earlier groups.
I like to have students work in groups of 2 or 3 for this activity. I find that there aren’t any “must have” supplies; it’s mostly important to provide a the widest variety of materials as possible. I generally have small class sizes; if my classes were larger, I would modify the project by having each group present only some of the organelles they modeled rather than all of them.