Teaching essential concepts in the sciences in kindergarten helps the students grasp the world around them in a more appreciative way. However, a kindergarten teacher cannot explain the complexities of gravity like a high school physics teacher. Instead, it is best to present visual and safe experiments that show how gravity works.
Gravity may be hard to explain to kindergarten students. However, you can simply state some famous sayings, such as "what comes up, must come down," as a general definition of gravity.
Dropping objects from safe distances is one fun experiment on gravity. You should use two objects, a light object like a feather and a heavy object like a book. Drop both objects at the same time and let your class observe the rate at which both objects drop.
A pulling experiment shows how gravity works on slow objects as well. The example of syrup, molasses or water dripping from an object should be conveyed to the classroom as gravity in action.
Center of Gravity
Showing how there are centers of gravity is not too complex for kindergartners to understand. You can show balancing experiments, such as balancing an object on a tip of a pencil, to show how gravity allows the object to maintain its balance.
You can allow your class to make small model cars. These small model cars can be placed on car chutes. The key to the activity is that you and the class can add more weight to the car. Encourage your class to notice how the car travels down the chute faster when it has more weight on it.