Today’s Wonder of the Day was inspired by Nathaniel from Oshawa, Canada. Nathaniel Wonders, “Why do houses have windows?” Thanks for WONDERing with us, Nathaniel!

How do you wake up in the morning? Does an alarm clock's shrill scream alert you? Or is it a parent's gentle voice and nudge that tells you it's time to get up? For some, the signal of morning is the first rays of the Sun peeking in through the bedroom window.

Once you're up and moving about, how do you decide what to wear for the day? Many people look out the nearest window to see what the weather is like outside. Raindrops or ominous clouds may mean it's time to get out the poncho and rain boots.

As you sit in class, you may WONDER whether the rain has given way to sunshine. Hoping for an outside recess, you may find yourself gazing out the window every few minutes as the clock's minute hand inches ever closer to recess time.

What do all these scenarios have in common? Windows, of course! Usually we don't give very much thought to the window itself, because it's what's on the other side of the window that we're focusing on. Unless windows are part of your job or passion, you might take it for granted that you can see what's going on outside without being outside. Most people never give much thought to the fact that, for thousands of years, that wasn't the case.

The earliest structures built by primitive people were crude, windowless enclosures with two primary considerations in mind: keeping out the weather and protection from wild animals or other hostile enemies. Light could only enter through whatever opening served as the door and a small hole usually made in the middle of the ceiling to let out smoke from a fire.

Can you imagine living in such a dwelling? In addition to being dark, it was probably a bit dangerous not knowing whether rival tribes or wild animals were lurking outside. At first, windows were simply holes in the walls of dwellings. As time progressed, people began covering windows with things like with wood, paper, or animal skins.

The word "window" can be traced back to the Vikings and the Old Norse word vindauga. Broken down, the individual words are vindr (wind) and auga (eye), which is fitting, considering windows protect from wind and rain while also allowing you to see outside.

Early windows were made from a variety of materials, including cloth, wood, oiled animal skins, and translucent stones. Paper windows were also popular in ancient China, Korea, and Japan. The first ancient peoples known to have used glass for windows were the Romans.

Ancient Roman glass windows didn't exactly look like the windows we have today, though. They were small and thick, because they were made by flattening blown glass jars into sheets. They let light filter through, but they weren't transparent enough to see through clearly.

It would be about a thousand years before transparent glass windows were used commonly in ordinary homes. For example, such windows weren't widely available in England until the early 17th century. Our modern floor-to-ceiling sash windows are an even more recent invention. Such windows didn't become possible until industrial plate glass manufacturing processes were invented.

Wonder What's Next?

Tomorrow’s Wonder of the Day will appeal equally to wallflowers and social butterflies!