How BIG is BIG? is a kids book that I have been writing and illustrating for about 3 months now and is finally (I hope) ready to send off to the printers.
The book follows the adventures of three characters: Olivia, Oscar and Orin who discover how size is relative to your perspective. So what I mean by this is how big something appears to you both depends on your size and how far away from something that you are. An example of this would be when you are a small child all adults look big but when you have grown in to an adult some are big and some and small.
How BIG is BIG? follows a story line to explain this graphically to children. There are lots of facts along the way that the kids can learn. The language is pretty simple to make it accessible to as wide a range of children as possible. The book is aimed at children from about the age of 4 through to those aged 14.
Below are a couple of images from the book.

How BIG is BIG? cover

How BIG is BIG? volcano page
They are the front cover of the book (top) and one of the internal pages (bottom) where Olivia (the purple elephant) asks how big volcanoes are. To which Orin (the red elephant) reply’s and there two callout boxes with some interesting facts about volcanoes. The dimension or size of objects that the characters discuss is given both in metric units as well as in ‘elephants’.
The idea of using elephants to provide a unit of measurement is to help kids to get a grasp on how big things are, to make them less abstract in terms of a number of metric units and turn into something that they can relate to, with many children having seen a real elephant in the zoo.