Attach key words randomly to the wall of your teaching area. As the pupils come in, give each one a piece of paper with the definition of a certain key word on it. They need to find the right key word and stick their definition up next to it.
Then (maybe while you call the register), they should check all of the others and see if they can spot any that seem to be in the wrong place.
Obviously there are many variations on this idea which you could also try. You might put the definitions on the wall and give out the keywords instead. Alternatively you could ask pupils to match “ideas” to “evidence”, or “questions” to “answers”, etc. You could also have one word or idea which needs to have more than one thing attached to it.