most MATs look for
listening and awareness.
I don't know which school/area you are preparing for but most schools
expect some keyStage 2 music ski11s.
try the BBC schools Music website.
at least you can hear some music to get yourself more acquainted with what is coming.
Most are done 'on the piano' like a normal music grade exam
so if you have a keyboard, you can try out the exercises that T.i.p.s.y outlined
so your child can sing the required notes or clap back to you.
Even random chords/scales wi11 provide some familiarisation.
Does your child have a music teacher?
They usua11y know how to prepare for these sort of tests.
You could also listen to radio 4 during car journeys to try to pick out notes and 'la' along.