At times I feel that this "intro" to cosmology is almost TOO intro! It's hard to do justice to the complexity of a century of inquiry in just a few minutes. But these episodes are really designed to lead you to the main "players" in the game. And the story of the universe in the 20th century is not told without mentioning Lemaitre and Hoyle.

If you ask your students who the biggest opponent to the theory of the Big Bang was, they likely will say the church. That is actually incorrect. The biggest opponent was the scientific community because the main idea was that the universe was STATIC and unchanging. The person leading that parade was Albert Einstein who told LeMaitre that his math was fine but his physics was atrocious!

Einstein, LeMaitre and Hubble all met together to discuss their repsective ideas of the universe, and eventually Einstein realized that the data was correct and the universe IS expanding. He referred to his cosmological constant as his biggest blunder, because he had formulated it to counteract the possibility that the universe was in motion.

Truly one of the greatest scenes in scientific history would have been that epic conversation between these three great scientists. Maybe have your students act it out and re-enact that pivotal moment in our understanding of the universe.