This flowchart's quite funny, and it's also useful to practise modal auxiliaries (If you like furry tails, you must / you should / you could / you can't...), negative forms (People who can't stand cold blooded animals will not / are not going to /...) -and specific vocabulary too : you can revise and improve it by finding other animals in the same category/species as the ones pictured on the illustration.
Last, but not least, more advanced learners may train their writing skills...
Caldwell Tanner's flowchart pretends (1) dogs are "companions", while cats (or rabbits, hamsters...) are "roommates you have to feed" : do you agree with him ? Why (not) ? Explain your answer and illustrate it with examples :o)
(1) Beware, "pretend" is a false friend to French learners -check it !
Flowchart created by Caldwell Tanner (currently head illustrator for collegehumor.com website)