Cupoftea I hope you don't mind me posting this but a very kind friend gave this to me to read to my dd when Erin died. It might help your girls to understand:
Down below the surface of a quiet pond lived a little colony of water bugs. They were a happy colony, living far away from the sun. For many months they were very busy, scurrying over the soft mud on the bottom of the pond. They did notice that every once in a while one of their colony seemed to lose interest in going about with its friends. Clinging to the stem of a lily, it gradually moved out of sight and was seen no more.
'Look!' said one of the water bugs to another, 'One of our colony is climbing up the lily stalk. Where do you suppose she is going?' Up, up, up it went slowly. Even as they watched, the water bug disappeared from sight. Its friends waited and waited but it didn't return. 'That's funny!' said one water bug to another. 'Wasn't she happy here?' asked a second water bug. 'Were do you suppose she went?' wondered a third. No one had an answer. They were greatly puzzled.
Finally one of the water bugs, the leader of the colony, gathered its friends together. 'I have an idea. The next one of us who climbs up the lily stalk must promise to come back and tell us where she went and why.' 'We promise', they said solemnly.
One spring day, not long after, the very water bug who had suggested the plan found himself climbing up the lily stalk. Up, up, up he went. Before he knew what was happening, he had broken through the surface of the water, and had fallen onto the broad, green lily pad above.
When he awoke, he looked about with surprise. He couldn't believe what he saw. A startling change had come to his old body. His movement revealed four silver wings and a long tail. Even as he struggled, he felt an impulse to move his wings. The warmth of the sun soon dried the moisture from the new body. He moved his wings again and suddenly found himself up above the water. He had become a dragonfly.
Swooping and dipping in great curves, he flew through the air. He felt exhilarated in the new atmosphere. By and by, the new dragonfly lighted happily on a lily pad to rest. Then it was that he chanced to look below to the bottom of the pond. Why, he was right above his old friends, the water bugs!. There they were, scurrying about, just as he had been doing some time before. Then the dragonfly remembered his promise: 'The next one of us who climbs up the lily stalk will come back and tell where he or she went and why'.
Without thinking, the dragonfly darted down. Suddenly he hit the surface of the water and bounced away. Now that he was a dragonfly he could no longer go into the water. 'I can't return!' he said in dismay. 'At least I tried, but I can't keep my promise. Even if I could go back, not one of the water bugs would know me in my new body. I guess I'll just have to wait until they become dragonflies too. Then they'll understand what happened to me, and where I went'.
And the dragonfly winged off happily into its wonderful new world of sun and air.