[QUOTE=IntelSoldier]
…Make sure you make two points clearly. In the close picture, gravity pulls downward. In the earth picture, gravity is just pulling toward the middle, not down.
[/QUOTE]
One thing I always discussed was what “down” means exactly. Start by asking students which direction is “down”? (Most students will point toward the floor.) Expand on this by asking what someone in Australia would say. Are they pointing in the same direction as you? End up by emphasizing that “down” means “toward the center of the Earth.” I would not recommend saying that the force of gravity due to the Earth doesn’t pull “down.” It does.
[QUOTE=IntelSoldier]
…Try throwing in the phrase “The astronauts are falling toward the ground, but the ground is falling away from them.” They won’t (shouldn’t) take you literally, and that might get the few slow ones to understand.
[/QUOTE]
You can use this phrase, but you need to emphasize that the reason the ground is falling away from the orbiting object is because the object has sufficient tangential (sideways) velocity.