We planted some apple seeds this Spring and they did very well. We just moved them inside for the winter and now the leaves are turning colors? Are they dying or just going dormant? If dying, what did we do wrong and is there anyway we can help keep them alive? Apple sapling 1
They look as if they were going dormant outside before you brought them in. If they are now in a warm room, quite likely they will start to grow again too early and end up etiolated because of the low light level inside the house over winter.
Keeping them in normal "living room" temperatures is not a good idea. They really need several weeks below 50F (10C) over the winter period to grow naturally with a dormant period over winter. Keeping them somewhere unheated (e.g. a garage) would be better.
If it doesn't get a proper dormant period, it just will keep growing one long stem. A dormant period will make some of the buds along the stem "break" and grow into branches next year, so you will get something that starts to look like a tree.
Unless your climate is too cold for apples trees to survive the winter anyway, I think they would have been perfectly OK left outside.