The common ancestor and evolution by natural selection, concepts introduced by Charles Darwin, constitute the central core of biology research and education. However, students generally struggle to understand these concepts and commonly form misconceptions about them. To help teachers select the most revelant portions of Darwin's work, I suggest some sentences from On the Origin of Species and briefly discuss their implications. I also suggest a teaching strategy that uses history of science and curriculum crosscutting concepts (cause and effect) that constitute the framework to explain the evolutionary history of ratites (flightless birds) as described by Darwin, starting in the Jurassic, with the breakup of Gondwanaland, as first described by Alfred Wegener in The Origin of Continents and Oceans.