Science is a process, not a list of facts, so why not illustrate that by teaching about obsolete notions and discredited theories to give a background for those which currently are accepted?

I was fortunate enough to have received an education that did this to a certain extent, so I know that there are lots of interesting theories out there to explain the evidence against.

In Physics talk about the Flat Earth Theory, crystal spheres, epicycles, and the Luminiferous Ether.
In Chemistry talk about the elemental theory involving Earth, Air, Fire, and Water. Discuss the search for the philosopher's stone and the development of the periodic table, and explain how our understanding of the atom developed.
In Biology discuss Young Earth Creationism, humours, and Lamarckianism.
Talk about subjects such as phrenology and perpetual motion to let students know why such things are called "pseudo-science". Help them understand how the process of science refines our knowledge of the universe and makes modern life possible.

This earnest plea has been a nodeshell rescue.