Water is a pretty awful material for building. Yes, it's abundant and cheap. Yes, it can be made opaque or translucent or even pretty transparent. Yes, you can use it to make buildings (like in that totally awesome James Bond movie), but there are a few drawbacks.

It's slightly unstable in the warmer climates. It's vulnerable to destruction from dogs marking the walls. Ice chairs make your hiney all cold.

So this video isn't really about materials, but it is a great background video on the chemistry of water, something that most of our materials run into from time to time.

The chemistry explanations are fairly in-depth (electrolytes, polarity, moles, molarity, anions, and such), so this may not be for all of your students, but it's a great bit if chemistry.