The practice should be setup as shown. Have one player as a wicket keeper and another as fielder.
The bowlers take it in turns to bowl, with the fielder calling if the ball was a good line (pitched in the cones) or a good length (pitched level with the red hoop).
If the ball pitches in the hoop then the ball is both a good line and length.
Organise the group into pairs and set up the activity as shown in the diagram. Ball is bowled to partner from the coil position. Partner catches the ball and bowls it back.
The ball must bounce before reaching the partner.
For this you will need benches and chairs. Place the benches and chairs a distance away from the children. Spread cones out on the benches, chairs and floor. Put a large ball on each cones (assorted colours for scoring). The children must try to hit the ball off the cones using an overarm bowl. You can adjust the scoring to suit what your children are learning in numeracy.