Machines are inventions that make work and other tasks easier. Simply stated, there are two types of machines: simple machines and compound machines. There are six simple machines: a lever, a wheel and axle, a pulley, an inclined plane, a wedge and a screw. Compound machines are made using two or more simple machines. Learning how to make a compound machine requires a little brainstorming and experimentation. The process can be easier if you work from an example and experiment on your own.
Brainstorm for five minutes and think about the six simple machines and how each one functions. Examine a few compound machines to spark the through process. Work from a problem; assume you have a piece of wood and you need to split it into two pieces.
Choose two simple machines and hypothesise about how the two machines can help you complete your task. To split a piece of wood, for example, you might choose to use a wedge and a lever.
Combine the two simple machines in various ways and ask yourself whether the compound machine makes the problem easier or more convoluted. Keep in mind that the purpose of machines is to lessen the amount of work that needs to be done on your part. As an example, if you choose to use the wedge and lever to split a piece of wood, you might attach the lever to the wedge so that the sharp/narrow edge of the wedge can be swung at the piece of wood. Essentially, you have created an axe.
Experiment with the compound machine to see how changing one or more of the simple machines makes the task harder or easier. For instance, if you increase the length of the lever in your makeshift axe, you can swing the compound machine with more force than you could if the handle was shorter.
Experiment with other simple machines. For instance, you could combine two or more pulleys to make lifting objects easier. You could use a screw and a Phillips screwdriver (which is essentially a lever) to attach a shelf to a wall. You could place an inclined plane near a raised surface and use a wheel and axle to push heavy objects up and over the raised surface.