What Your School Bag Is Made Of

The story

Right now, somewhere in your home, your school bag is resting between adventures. Let's find out what it actually IS — because that bag is a little piece of engineering, and it has travelled farther than you might ever guess.

Start with the fabric. Rub a typical school bag between your fingers and you'll feel it: not soft like a t-shirt, but tough. Look VERY closely at most bags and you'll see why — the fabric is woven, like a tiny basket. Thousands of skinny threads cross over and under, over and under. And those threads are usually not cotton. They are plastic threads — most often one called nylon or one called polyester — made in factories by melting plastic and pulling it out into fibres finer than hair, then spinning and weaving them tight.

Why plastic threads? Three good reasons. They are strong — hard to rip even when you stuff in one book too many. They shrug off a light rain — especially with the coating many bags wear — helping your worksheets stay dry. And they are light, because YOU have to carry every extra bit of weight. Strong, dry, light: that is the fabric's whole job.

Now the straps — the cleverest part of the bag. Inside most padded straps hides a slab of squishy foam, full of tiny air pockets. When the bag pushes down on your shoulders, the foam squashes and SPREADS the weight out wide, so no thin strap digs a line into you. And two straps, worn properly on both shoulders, share the load between both sides — doctors generally agree that for an ordinary backpack, two straps beat one slung shoulder.

And the zips! We could tell a whole story about zips — those rows of tiny teeth folding together like your fingers folding together — but for now, just know this: the zip on a good bag gets opened and closed thousands and thousands of times, so bag makers test them. In some factories, machines sit there all day zipping and unzipping, zipping and unzipping, counting to enormous numbers, to make sure YOUR zip won't quit halfway through the school year. Machines are also made to tug straps again and again, and to stuff and shake bags, hunting for the weak spots before you ever find them.

Then think about the journey. The threads may have been made in one country, woven into fabric in another, dyed your favourite colour, cut and sewn together with the foam and the zips and the buckles — often in yet another country — then packed into a box, onto a ship stacked high with containers, across the sea, to a shop, to you. Many hands and machines — often in several countries — for one bag.

So the next time you swing that bag onto your back — pause one second. A whole world of makers built this thing to carry your world. Wear both straps, and off you go.