Jacks is the name of a game that is quite popular with children. To play jacks you will need a small rubber ball and ten small metal objects (物体)called jacks.
The rules for this game are not complicated (复杂). To begin, you put the ten jacks on the floor or ground in front of you. Throw the ball up but not too high, pick up one jack, and then catch the ball. Keep the jack in your hand and then go on picking up the other jacks one at a time. You lose your turn if you do not catch the ball, you do not pick up a jack or you drop any jacks from your hand.
When you finish all ten jacks, you now try to do the same thing again but with two jacks at one time. This is more difficult, of course. You lose your turn if your make any of the other three mistakes or if you do not pick up exactly (准确地)two jacks each time!