Most asteroids are found in the Asteroid Belt, between Mars and Jupiter. Some asteroids are actually in the same orbit as Jupiter but they won’t collide with Jupiter, these are called Trojan asteroids. Other asteroids have passed very close to Earth. These are called Near-Earth Objects or NEOs.
If you stuck all the asteroids together, you would have an object that is much smaller than the Moon.
Our Hunting for Asteroids workshop allows students to detect asteroids and calculate their speed.