I have done tons of these as part of an after school enrichment program. From 5 years to 12, and then once for senior citizens. I have discovered that even a 3 twist dog is cool when "you make it yourself".  The key is plenty of encouragement and lots of humor. Pioneer party group sells a pump great for small/old hands, easy action and not the spindle type that snaps. I attached a photo to show you the size between the standard red Qualatex pump and the one I am describing.