So while playing Mary Had a Little Lamb, you'd work on Pathetique? That is the level of this boy - single note melodies distributed between the hands, with maybe a couple of chords thrown in.
And he insists on learning Moonlight Sonata and Fur Elise?
Tell him it's like trying to do advanced math (Algebra, Geometry, Statistics, Calculus) without knowing how to add and subtract. In fact, show him the math curriculum, and point to where he is--at the bottom--and that in schools it will take about 8 more years to get to Algebra, and 11 more years to get to Calculus. That's measured in YEARS.
I don't get such moronic requests from my students, but once in a blue moon a parent would be dumb enough to ask. The last time that happened, the query came from the kid's grandma. I told her the kid can't even read notes fluently yet after four years of "lessons" from hack teachers. This kid came to me playing Fur Elise (the first section) by rote, and I immediately sent him down to the Primer method book for ZERO reading ability.
Another recent request came from the mother of an advanced student asking for the third movement of Moonlight Sonata, and I just laughed in her face--but in this case the kid is so much further along, so why bother learning something so trite and rudimentary??? We have MUCH more difficult music to work on.