Copied from Englipedia's description of their This/that relay post.
Three sets of matching cards (not included): One set should be A4 size, the other two can be small playing-card size
Put the two small sets of picture cards around the room. The third set of cards is with the JTE or ALT.
Break students into two teams. Two students compete at one time. The ALT calls out one vocabulary word: monkey. The two competing students run and find one of the monkey pictures each. Meanwhile, the powerpoint shows the silhouette of an animal, for example, a frog .
The first student to find the monkey card and say "This is a monkey. That is a frog." pointing to the TV receives two points, and then if the other student can find his/her picture and make the sentences also they receive one point.
This is very repetitive, so kids may get bored, especially in big classes. Make it varied, high energy, include ways to get bonus points to keep students interested. Another way would be to make it smaller teams, so more teams competing (maybe more sets of cards are needed to make it fairer).