Start with checking out all the internet action already going on to get them aquainted with what sports and athletes they might be interested in. Check out the live feed from www.nbcolympics.com or get lots of info at www.olympic.org ! Google "Olympics" for more sites ...
Then ... do some training and competition! It is so important for children to have lots of exercise and physical movement - get out there and make it happen! It's easy to put together a simple program of activities using items you may already have around the house or classroom.
See what you can come up with ... when we did the Winter Olympics, we set up a card for each "competitor," with different stations for "events" like sock skating and olympic ring toss (hula hoops and bean bags!). If you do a few games or exercises each day, you can stretch it out over a few days or a week - culminating in a Closing Ceremony of your choice!
Crafts can be simple:
For olympic rings, you'll need paper, paint (representing each of the five colors) and small paper cups! Hold the cups upside down, dip in paint and print circles galore!
For a related art project, make Olympic torches! Trace children's hands on flame-colored tissue paper - red, orange, yellow - one set of each if you can! Wrap a paper roll with black paper or have them paint them black and then attach the hands to the top - now you have Olympic torches!