Here's a nice little animation:
It shows the five inner planets, together with the sea of asteroids they're moving through. The yellow dots are Earth crossing asteroids. The blue dots are asteroids that don't cross Earth's orbit. The Sun is at the center, of course, and the Earth is the third large orbiting dot out from the center. We're zipping around through some fairly congested space.
I don't know how we keep missing Venus let alone all those yellow dots!
Not even close, except in the hysterical graphics that passes for science these days. Certainly not as congested as that graphic suggests. NOTHING IS TO SCALE!
Kids of all ages are not as dumb as we adults assume. The can certainly grasp the concept of relative distances and sizes.
I suggest these two sites as a start in understanding the distances and sizes involved :
Even the "science" satellite TV channels dumb things down to silliness. Not really necessary.
That is great graphic