Here is an introduction from a student project in my physics course, who investigated issues of symmetry in projectile motion:

“Why choose this subject to investigate? Out of all the options to research, why this one? The main and best reason I can give to explain why I chose this is just out necessity… In class, …through visualization [of motion diagrams]we began to realize a possible connection between the upward and downward segments of the path. We started to see the motion as reversing itself after the object reached the top of its path. It was from this, that we as a class began to form that idea that if you throw something up at a specific speed, then when it comes back down and gets to the same height that it must be moving at the same speed.”

And here is another introduction from a different student studying the same phenomena

“The purpose of our experiment was to determine if the speed of a ball being thrown up is equal to the final speed of same ball going down. The motivation for this experiment was in part based on Galileo’s own experiments with gravity. Galileo, an Italian physicist, determined that the force of gravity is constant and objects fall at a constant acceleration toward the earth. He determined this by dropping two cannonballs of different size off of the Tower of Pisa. The law of parabolic fall states, “The distance traveled by a falling body is proportional to the square of the time it takes to fall.”

There are likely many different things to see and ways of responding to these different introductions. But, these two different introductions tell the story about the difference between ideas and concepts. Kevin Pugh, an educational psychologist, writes here about ideas: “Ideas are possibilities that must be acted upon and tried out… Ideas are ways of being in the world… They are inseparable from human experience.” Writing about concepts, he states, “Concepts are established meanings (classics)…When intellectual products attain classic status, they become isolated from the conditions in which they had an original signiﬁcance and from their potential consequences for everyday experience. As a result, their importance is reflexively accepted, but not fully appreciated…”