Being responsible doesn't have to be boring. Children can learn a lot about taking care of their entire physical and mental being, including the part that needs to have fun, by spending time with a feline.
Play is a necessity for kittens to learn how to hunt and defend themselves in nature, and these instincts don't disappear just because a cat is domesticated. When your cat bats at a toy or jumps in the air to swat at a fly (or bracelet, or nothing at all), he might appear to be goofing off. However, these actions reinforce skills that any cat would need to survive in the wild -- like Mr. Miyagi having Daniel "wax on, wax off," they're actually building muscle and reflexes. Likewise, when children play games with friends or engage in activities like arts or sports, they learn a variety of life skills, from teamwork and creativity to fitness and problem solving.
Encourage your kids to spend time playing with your cat, too. Both cats and children need the mental and physical exercise that playtime provides, and the bond created will help your child grow into a caring, responsible adult.