I like the example of a clay ball and car/bicycle wheel/rim, as it's easy to understand. For instance, a clay ball has little value on its own. But by removing some clay from the centre to turn it into a bowl or cup, it becomes more valuable, even though there is less clay. Same with a wheel rim. A solid block of steel doesn't have much value beyond its raw material. But by shaping it into a circle and removing material from the centre to create spokes, it now becomes light enough to be a wheel, and is more valuable, despite there being less steel. The formal laws of logic would state that the more of something you have, the more valuable it is. But here the opposite is true, by having less of something, we have made it more valuable. How can this be, it's a contradiction! However, the contradiction is synthesised by understanding that the labour to remove material from the object in a specific way, so that the object can be used to complete specific tasks, has drastically increased the use value of the object, to the point that is is much more valuable than the raw material it is made out of. The lack of material in certain locations actually makes it very valuable. That is dialectics.

This is paraphrased from an explanation of Zhongyong Dialectics that I saw a few years ago. I hope I didn't screw it up too much.