The book If You Hopped like a Frog by David Schwartz is full of interesting facts that help students visualize and think about proportional reasoning.If you hopped like a frog, he says, you could jump from home plate to first base in a single bound… Since frogs are able to jump 20 times their body length, so too would a human being. He speaks about ants and snakes and other creatures in the same way, and uses proportional reasoning and amazing pictures to help students see what would happen if they too had the same abilities.
The discussions after reading this book are rich. Having students create their own book or page like David Schwartz has done would be a great task to carry on from the conversation. I have uploaded a selection of related problems (frog problems) that I found on the internet that I quite like, especially since they steer clear of the imperial system (which is featured in the story). The problems are set out on a series of 20 cards – enough to share between 2 or so kids in an intermediate class. I’d like to credit the author but can’t since there was not name on the problems, but you can find them and the whole document at this address