These chords are in group B of the technical exercises and will make up the basis of many of the songs you'll learn at this and even the next grade.
The chords covered are: A, D, C, G, A minor and E minor.
It's really important to be able to play these chords well and change between them smoothly, so practise them a regularly. Once you can do this, you'll be able to play many, many songs not just those in the Rockschool grades, especially if you have a capo.
These chords are all 'open position' chords, which just means they are played at the end of your guitar and use at least one open string.
When you first put your fingers in position, play each string on its own so you can hear if they sound good. After this though, each chord should be strummed using either your thumb or a plectrum (pick). Try to get a nice even sound from each string when you do this and use a light movement - don't press hard on the strings with your thumb or plectrum (pick).
Once you can play the chords, try playing them in different orders. You could try writing each chord on a small piece of paper and mixing them up. The pick one out and play it.
Here's the video lesson: