The best way for children to understand what Rosa Parks did is by acting it out, so put on your own demonstration in your home or classroom. Set up your own bus out of chairs and choose one child to play Rosa Parks while the rest play angry riders. The child you choose to play Rosa should not be a very emotional child, or having others yell at her will be upsetting. When you're done, ask everyone to explain how they felt about their characters.
Creative writing is a valuable skill for any child to practice, whether he's 8 or 18. There are many different angles that children can find when writing about Rosa Parks, so you may let them choose their own direction. If you prefer that everyone write on the same topic, ask children to write a story about the day on the bus from the perspective of someone who was there or a story about how the world might be different today if not for Rosa Parks.
Although Rosa Parks is known for one brave action, she devoted much of her life to public service and civil rights. Creating a timeline about her life teaches children about all her contributions so they remember her for more than just what she did on one day. Timelines also help children keep historical events straight in their heads. Ask each child to make a timeline of Rosa Parks' life on a long piece of paper. Help them research her life in order to fill it it in.
Many young children learn more through visual aids than they do from listening to a story, so creating a book about Rosa Parks will help them understand her legacy better. For preschoolers, write up several sentences summarizing the important things that she did. Write each sentence on its own paper and ask children to illustrate it. When they've created drawings for each page, staple them together to create a book. Older children can write their own words as well as drawing pictures.