> You can't reasonably keep compressing centuries of progress into an intro series. Reductionism can lead to simplification, which will take less time to teach

> You can't reasonably keep compressing centuries of progress into an intro series. Reductionism can lead to simplification, which will take less time to teach and learn. Take planetary orbits as an example. There was a time when people would have spent a lot of time learning about all the complicated movements the planets make through the sky, "spheres within spheres", retrograde movement and so on. These days we teach Newton's laws of gravity and a heliocentric model (both of general application). The motion of the planets then pops out almost for "free".