It is true what you've heard about elephants -- they can't play hopscotch because they can't jump. Well, all right, maybe they could, but they never do. If you were that big you probably wouldn't jump either unless you were looking to destroy your knees. They can be trained to step up and down off of platforms and sit back on their haunches, but they will not jump.
The truth is that they cannot jump up the way we can. Their musculature is not designed to expend the energy needed to propel that much weight upwards. However, this does not explain their not jumping off of something where there is no upward momentum. In that case we are back to the knees.
This may also have to do with elephant feet. While they have the same number of bones in their feet as many other mammals, they have them arranged so that they are actually walking on their tiptoes, something like cats. However, cats are more specifically designed for jumping and leaping, with their musculature basically being a large spring.
Elephants can swim. They've been known to be found swimming far out into the Indian Ocean. This isn't that surprising when you consider that fat floats and that elephants come with a built in snorkel.
Elephants are also NOT afraid of mice. They may become concerned or agitated if they hear mice scurrying about and cannot locate or identify the noise, but elephants are not an animal that is so easily scared.
With all that elephants have going for them, it hardly seems to matter that they can't jump -- unless of course, they wanted to take up hopscotch. But they seem to be more intelligent than that.