You particularly know you have a science kid on your hands when...
Your DS2.7 is awaiting his first balance bike's arrival in the mail. He's excited and was discussing overcoming any upsets and latent fears of falling off the bike: "Riding your bike is a great way to stretch your amygdala. It's also a good way to use your cerebellum."
As he was drifting off to sleep, he came up with this: "Mama, do you know what a funny word is? Lacrimal caruncle. Ha ha ha, caruncle!"
One project we're doing this week is a life-size diagram of the different systems in DS' body. In planning the design, DS specified explicitly that he wants "pretend mannequin eyes" and "everything MUST be made of cells."
This all in the 5 minutes prior to bed. I know people here will sympathize.