My class just finished a unit on plants, living things, and life cycles. This perfectly coincided with Earth Day and Arbor Day. I had my students choose one of these activities to complete independently or in a small group (depending on individual needs). On Arbor Day, we invited some parent volunteers and went outside to plant trees. When we finished, I had my students set up their projects in a "museum" style. We invited parents and other classes to come see their work. The kids really enjoyed the freedom of choice and creativity!