Asking infants to do a crossword is challenging, so instead you can get them to make one. On a whiteboard draw out a template and ask the class to come up with words, and the clues that correspond to the words. Once it's complete, the class can then reread the clues and fill in the letters on the board. The activity encourages children to think of vocabulary words and what they describe or are used to do. For smaller groups, a large sheet of paper can be used instead.
Print a number of images showing active or busy scenes, where there is plenty to describe. Infants must try and keep talking for a full 20 seconds about what they can see in the image. If they stop talking, they lose. This encourages children to slow down their speech and use as much vocabulary as possible.
Create a list of adjectives that the group will be able to understand. Infants must shout out the opposite of the word -- e.g. "slow" if "fast" is called out -- as soon as possible. It encourages reaction speed.
Create a list of objects familiar to the group and ask an infant to select one of the items from the list. The infants must then ask questions about the object to work out what it is. The game gets them to make connections between objects and what they do.
Show the group a small piece of television footage and ask them to shout out when they see a certain object. Make sure you select a suitable piece and work out exactly when the object will appear on screen, so you can listen out for which child shouts first.