Drawn to scale means one ruler for everyone
"To scale" means every animal in the picture is shrunk by exactly the same amount. If the picture makes a cheetah ten times smaller than real life, it makes the lion ten times smaller too. That way, if the lion looks a little longer than the cheetah in the picture, it really is a little longer.
Most pictures of animals are not to scale. A book might show a mouse and an elephant the same size on facing pages. That's fine for looking at them, but it can't tell you how big they are next to each other.
Long or tall?
Most animals are measured from the tip of the nose to the tip of the tail, so we size them by their length. A few animals are measured by how tall they stand: a giraffe, a penguin, a kangaroo. For those, the drawing's height is the number we use.
Some animals have only a height at the shoulder on the pages we trust, like an elephant or a zebra. Then we line up the drawing's back with that height. Each drawing on the stage says which number it was sized by: long, tall, or at the shoulder.
Why the bee needs a magnifier
Put a honey bee next to a blue whale and the bee is too small to see at all: thinner than a hair on your screen. It is still drawn there, at its true size, as a tiny dot. To let you see it, Pip the pangolin holds up a magnifier in the corner and draws the small animal zoomed in, and the caption says how many times bigger the zoomed one is drawn.
The magnifier only comes out when one animal is more than twenty-five times the size of the other. Below that, you can see both without help.
Measure yourself against the child
The child on the stage is our ruler. She is drawn at a height that is about right for a child in the early grades of school. Stand against a wall, ask a grown-up to mark your height, and compare it to her. Then you'll know how many of you would fit along a crocodile.
For Big readers: why drawings and not photos
A photo is taken from wherever the camera stood, so things near the camera look bigger. To compare sizes fairly, every animal has to be seen from the same angle and the same distance. Drawings let us do that: each one is a side view, like a field guide's plate, and its width is the animal's measured length.
The drawings are simple on purpose. They show the shape and the size, not a face, because the stage is a measuring tool. Each animal's page links to its sources if you want photos and more detail.
Pick Big at the top to see the part for older readers.