To give the students a sense of the proportions of the earth that are land and water, we toss a beach ball that's decorated as the globe. These are available inexpensively. As they catch the ball, they must report whether their hands land on earth or on water. I keep track of it on the board. After every child has a turn, we tally up the results. Surprisingly, this works successfully. As an extension, the student can call out the name of the continent on which their hand lands.