Stacking boxes

 I think this one has been put in because the box, unlike the other one, stacks. Look at the shape of the box. It is a different shape at the front than at the back. If you took a second box (the same) and turned it round it would neatly fit on the little cut outs. So one way round they go on top of each other, the other way round they go inside each other. Look below. What do I think it could be made from PP (polypropylene). How do you think that bottle at the back of the box is made? Blow moulding . Click to see. That tin in there is steel plated with tin to stop it going rusty. Click here to see other methods of coating and plating. Notice inside the tin it is also coated with some white stuff I think it is very thin plastic, it protects the food inside the tin from contamination. Did you know that a tin can is mainly steel and 100% of the can is recyclable. Steel is made from iron and carbon. The iron is extracted from iron ore (Rock with iron in it) which is melted in a blast furnace (Look here for animation). You know if you were sorting rubbish you could use a magnet for some things. The only metal in common everyday use which is magnetic is IRON and since STEEL is made from IRON + CARBON it also is magnetic and since some cans are made of plated steel you could pick them up. Metals which contain IRON are called FERROUS metals (STEEL, STAINLESS STEEL, IRON and CAST IRON are examples). Metals which do not contain any iron are called NON FERROUS metals (ALUMINIUM, BRASS and COPPER are examples).
Turn 'em one way and they stack on top of each other. Turn 'em alternate ways and they fit inside each other for storing and saving space. How do I think it could be made - Injection moulding click to see.

You might be asked in the test how you could make thing stack. Just make sure you have had a bit of a think about it.