This is an intermediate pattern. The hat is working the interlocking block stitch in the round with single crochet in the back loop only brim. You will need two crochet hook sizes to work the hat, however, the size will determine which two hooks you need. The pattern is worked the same for each size only the hook size is different.

Adult - I (5.5 mm) for the brim, J (6.0 mm) for the body of the hat
Child - H (5.0 mm) for the brim, I (5.5 mm) for the body of the hat

You will need at least 3 different colors of yarn to work this pattern.