The Waldorf mom in me thought that a digital recorder ( like a tascam dr-40 ) was a sort of electronic wind instrument and I even wondered what kind of sound it will produce, since I have only ever seen ones made from plastic and wood. My bad, hehe.
Most people will assume the right thing though, that it's something that can record sounds and it's portable and easily saved/accessed using computers.
Anyway, this leads me to the suggestion that music lessons and immersion in the art of sound won't be a bad way of spending the summer... or having your kids while away the summer heat. Get them guitar lessons, let them loose in bad practice and suggest new instruments. Just let them create and express themselves through music so that when school time comes again, they would have been refreshed.
And you just might find a new something to bond over.
After all, Dads can easily teach their fave songs from way back when to sons and daughters. Music with backstories... what could be more delightful?