The shop at Designmuseum Danmark sells quite a few beautifully-designed and beautifully-made pieces in wood and I came across this carpenter’s folding rule there.

Different timbers are used for each section and on the back of each section the wood is identified with a drawing of the leaf and a short list of the most common uses for that timber: each timber has different qualities, different grains, different colours that make them suitable for some uses and not others.

I can’t think of many better or easier ways to start learning about types of tree and types of timber.