Casi Elaina, no te has caido
, a pesar de estar en terreno resbaladizo.
"pregunta al azar del día" it's a good term, but I prefer "Pregunta al azar diaria" sounds better to me, because as Elaina says, first is "pregunta al azar" then "diaria"
Other options
Pregunta al azar semanal ó de la semana
pregunta al azar mensual ó del mes,
trimestral, semestral, anual, bianual, trianual, quinquenal,........