This session is a bit more complex, but it is a good session, and keeps things interested. We have the Moneghetti Fartlek!

Broken down, with a warm up and a cool down either end, the session is:
2 x 90 seconds effort/90 seconds recovery
4 x 60 seconds effort/60 seconds recovery
4 x 30 seconds effort/30 seconds recovery
4 x 15 seconds effort/15 seconds recovery

This session is shorter (about 22 minutes), and should be run at your 5k race pace, and attempt to go faster on the shorter efforts if you can!