Grade 3 music theory requires you to identify and correctly lay out key signatures for:
The following video explains how to lay out all key signatures (of up to 7 sharps/flats) in four different clefs: treble, bass, alto & tenor.
Please note that you do not need to understand alto and tenor clefs at grade 3. You also do not need to know the layout of more than 4 sharps or flats. This extra information is provided for information purposes only.