Providing themes for learning is motivational for students.  It can be class wide, grade wide or school wide and as simple or involved as the planners would like.  Using Whales as an example, one can use multiple intelligences as well as more traditional learning modes to do an in depth study of  whales on our planet.  Reading as many books as possible about whales, students can then make whale books, do whale crafts, work on whale math, participate in whale centers and even turn the classroom/school into a giant habitat for sea life where whales are the main species.  If school wide, students could join together and make a life-size paper mache replica of a whale to be placed in a hall or multi-purpose  room  which would give perspective when comparing  the sizes of  whales and humans.