The Levers ebook that I'm working on is slowly taking shape. There will be some pull-the-tab moving pictures showing the principles of levers as well as information, some models to make and a bit about applying this knowledge to designing your own models.
I've been working on the page for the 1st order lever. That's a lever where the pivot point is in the middle between the force and the load, like a see-saw.
I've had fun making the arrows stay upright as the lever rocks, currently I'm using a slot to run the arrow in but this may change as the model is refined.
Notice the text in the page layout, I've used a temporary place holder, I'll be adding more diagrams and proper explanatory text later on. For the moment I have used the standard place holder text that has been used by printers since the 1500s. When printers and designers want to see how a page will look before they have the finished words they use the Lorem ipsum text. I used lipsum.com to generate a paragraph for me. The idea is that the lengths of the words, the mix of descenders and ascenders and the lengths of paragraphs give a page that looks just like normal text.