Run for a minute and switch working player. Player A serves underhand lob to B who heads to C. Player C serves A who heads to B, and so on. Emphasize moving entire body to enable powerful headers struck with forehead. This progression, and the progressions which follow, probably will be too difficult for players under about age 10-11. 5 yards between players.
Next lob comes immediately.
This results in the workingplayer having to deal with balls froma variety of angles, identify a target, and perform header. As players improve, increase distance and allow non-working players to move around. Working players set up in center of area. Run for a minute and then have players switch roles. Put several players around the edges of a large circle, with about 2-3 players inside circle.