You need a large ball of string (or wool if it’s sturdy enough – there’s some pulling!).
Sit the children in a circle and emphasize that they must remain in their seats (for safety reasons).
The game starts with a child or the teacher saying the name of someone else in the circle and holding on to the end of the string, while throwing the ball to the person they named. The receiver calls out the name of another child and keeps hold of his or her end of the string while throwing the ball of string onto the named child.
As this continues, a web begins to be formed by the crisscrossing string.
The fun really starts when the group has to undo the web by calling names and throwing the ball of string which is rewound by the receiver before sending it on (this idea was supplied to me by a teacher friend, Lorraine Webb).