Re: why does wheat absorb the most milk

Josh, you have done an interesting experiment, and as a result you have formed an hypothesis -- that Weet Bix absorbs more milk because it is made of wheat, rather than a different type of grain, e.g. rice in Rice Bubbles or Coco Pops.

The problem is that you are trying to base your rule on a single instance, and scientists have to be a lot more thorough than that. You really need to do further experiments to test your hypothesis. I have a suggestion to make:
There are more differences than just the grain between Weet Bix and Rice Bubbles. And they need not even be in the composition -- shape and texture could also be quite important.

A very good test would be to go to your local supermarket and get some puffed wheat (not such a popular cereal as those you have been working with, but readily available in most Australian supermarkets), and try your milk absorption test on that.

The point of using puffed wheat is that it has a grain composition similar to Weet Bix, but a shape and texture similar to Rice Bubbles. If you find that it is similar to Weet Bix, then your hypothesis is looking good (but still not proved by any means). If, on the other hand, you find that it is more like Rice Bubbles in its behaviour, then you will have to reject your hypothesis and look more closely at other factors like texture and shape.

Weet Bix and Rice Bubbles and Coco Pops are proprietary trade marks. I do not know about Puffed Wheat, but it may well also be.