Either use half a mini soccer pitch or mark out an equivalent area. The size will depend upon the age group.
4 + GK v 2
The objective for the goal keeper and the 4 defenders is to get that ball across the retreat line (halfway line) under control on 8 out of 10 attempts. Each attempt starts with the goal keeper taking a goal kick on the floor from the edge of his penalty area. When the keeper passes the ball to one of their defenders the two attackers can run towards the ball from the retreat line, one pressuring the ball the other providing cover. The defenders need to react to the movement of the attackers by exploiting the space, usually by passing the back and or across the pitch to exploit the width. The defenders have to get the ball across the line by either dribbling it or passing to a team mate who has made a run. Based on the numbers the objective looks quite easy for the defenders to achieve, but the attackers can prevent the defenders achieving the objective by either scoring a goal or getting the ball out of play. Making the objective much harder than it initially appears. If you have extra players rotate them with the attackers as it can be a tiring game for them.
Midfielders should run back to support the defenders in their attempt to get the ball up the field.
Receiving the ball without stopping it and away from the attacker.
Attackers should communicate and cover one side of the pitch.