Bingo. When I was a kid, I once flipped my bike because I was only braking with the front. I learned not to do that, but to an extreme — I then braked almost always with just the back.

It wasn't until I got older and faster that I realized that braking just in the back is not as effective, since the braking action makes your nose dive and puts more weight over your front tire. I now brake with both sides, but always first in the back.