If you have a flight of stairs at home you dont need to go to the gym to workout your quads and tone your body. Here are a few variations for you to try:

1.) Skip a step as you climb up the stairs.
2.) Jumping from step to step with just 1 foot on the stairs per movement.
3.) Walk up and down sideways
4.) Run up 2 steps and take 1 step back, continue til you reach the top.
5.) Get on all fours, and crawl up the stairs. (Left arm and leg move together followed by the right.)

While all of these are great forms of exercise remember to practice safety at all times keep a sharp eye on the steps and focus on the movements so you dont fall off the stairs.