The mice began to poop everywhere in their cage, kids started school and the fun of watching them started to wear off quickly. At night (remember they are nocturnal) they would run on the wheel in their cage and you could hear this loud annoying noise. By day 12 we were off to the pet store to return these little creatures. (16 day return policy, thank you PetCo) Kids got their money back minus the wheel. All in all it was a great learning experience. My kids learned that taking care of something this demanding isn't all its cracked up to be.
Many life situations you can't just return it... I hope they learned their lesson.