The playing field is marked by 6 cones as shown.
Four players are placed outside the grid and four attackers are placed in the field agaist 6 defenders.
A team of four and a team of six are identified with different colors in the middle.  
The outside players can be the wingers of the team, who practise the crossing skills. The team of four in the middle are basically the attackers and they try to score the crossings. The team of six are the defenders and they practise the defending requirements against crossing, and long areal balls.
The players' roles can be changed periodically.

Players outside perform crossings from differents angles. The attacking four try to score from these crossings.
Defenders' objective is to clear the crossings and perform switchover from defending to attack. If the defender anticipates the position of the crossing and there is a minor pressure from attackers, he has to play the ball directly to one of the team- mates and try to score.