“Boring,” George interrupted gently. “Say it like this : ‘That ball is lying to the air, pretending it wants to go up, but gravity always wins.’ Then pause. Then do the math.”

“It is on YouTube,” Missy said, scrolling her phone. “You need a catchphrase. Or a cat.”

Just then, the livestream comments loaded on the laptop. Most were blank. One user, “BillyBob42,” had written: “This kid sounds like a robot with allergies.”