range() and slice semantics

Does anybody have a nice, student friendly explanation of the 
"half-open" semantics of the range function and of slice notation? In 
other words, why does the list created by range(0,10) contain 0 as an 
element but not 10, and why does mylist[0:10] start with mylist[0] and 
end with mylist[9]? If you're an experienced coder, these semantics make 
sense in terms of the underlying implementation and the usual use of 
these objects as iterators, but if lists are new to you the behavior can 
seem a little mysterious. Thoughts?

Jay