I like to teach time using the One Hand at a Time approach. It focuses on teaching only the hour hand first. For instance, it's a little past 3 or it's just after 6. Eventually, they learn how the two hands of a clock work together-but only when they understand how each hand works individually. The book is by Patricia E. Smith through the Dale Seymour Publications. I use this along with a series of "slit clocks" which are made from paper plates and are self-checking. This is another single-handed approach to telling time. It's from Teacher-made Aids for Elementary School Mathematics from the Arithmetic Teacher. Both are supported by the NCTM. I've used this with second graders for years and it works great.