Another fun warm-up variation on tag from the Quebec PE site: Tusker Tag. Best for large groups.
Players pair up. All pairs must hold hands or wrists. One pair is designated Tusker. If you have an uneven number of players, include single player as one of the Tuskers also. Give Tusker team a ball. Commence playing 'tag'. Tusker team tries to tag other pairs with ball. Note they are touching other players with the ball still in hand, not throwing ball at them. When tagged, pair is frozen in place and must raise the hands they are holding up into a bridge shape. They may be unfrozen if any other unfrozen pair runs underneath their 'bridge'.
If any hands/wrists become disconnected, that pair is automatically frozen also.
Object is to tag/freeze all players.
Make this game harder by gradually shrinking the playing space. For example, start by using the entire end of court. Then shrink to back court only. Then to service box. Then alley. Any players stepping outside of boundaries are frozen.