This is actually the third year that my students have created up-close flower paintings while learning how artists create emphasis, and being introduced to the works of Georgia O'Keeffe.
I found one of the best videos on YouTube for teaching emphasis. You have to check it out. Here is the link https://youtu.be/rG9gx6kjDzI I do not own this video or anything, just found it while scrolling around on YouTube looking at nerdy art teacher videos.
After the kids are all jazzed from the video, and I have them identify what is most important, and how we know it is most important, in different artworks at the end of the video we do a few small exercises for them to show me that they understand how to use emphasis in their art.
Their flower paintings actually take several class visits to finish. On the first day they draw their flower and begin outlining it with sharpie. The second day, they start coloring in only the flower using oil pastels. I try to get them to experiment with highlights and shadows (few ever do), They do actually play around with and learn to use the pastels pretty well with this project. They are usually still coloring with oil pastels on the third day. The fourth day, we paint the background with water colors.
Another thing that I like about this assignment is that I get to talk to them about mixed-media. I explain that their paper is special paper called mixed-media paper. We discuss what media is, and why we need this paper to use different kinds of media. I also get to show them how to get bright colors, and not watered down colors out of their paints. This project also works well to review warm and cool colors. We use color temperature to help create emphasis. Students have to pick either warm or cool for their flowers, and use the opposite for the background.
Here are some more examples. Enjoy.