The Single Arm with Kick Board drill is excellent at isolating your stroking arm while keeping the other on the surface of the water. Hold the Kick Board at the edge, closest to your stroking arm, so that your hand and arm don't hit it as you finalise your recovery. It's important to rotate at the front and back end of your stroke, to gain reach at the front and extension at the back end - moving your body out of the way of your arm as it travels under your body. So the order is this:
Extend and rotate forwards, point your hand and forearm downwards to the bottom of the pool keeping your elbow high and making both act as a paddle, accelerate through the stroke as your arm travels under your body with your hand never crossing the centre line of your body.
Catch Up to Kick Board should be done with your hand leaving the kick board form the side not the back. That way you can continue the extension and catch position from the single arm drill.
The remainder of the session is quite easy to follow and is all about taking good form into speed and maintaining a constant and steady pace through increasing distances.