Word Bag is a fun game which helps with semantic fields and vocabulary in general. It's quick to set up and ideal to keep the class occupied for 10 minutes at the end of a lesson and it is very good for all ages and levels of students.
To start, divide the class into teams. Make sure that you have evenly balanced teams and feel free to move students around here. There can be as many teams as you want, but ideally you want about 4 students per team.
Each group should now pick a "secretary" to write down words. Have them clear away all books and bags and leave each group with just a single piece of paper and a pen.
Then give the students a topic. This can be anything relevant to what you have been studying so that with a business class you might choose something as simple as in the office or in your briefcase whilst a class of younger children might get in my kitchen or at school, etc.
Tell each group to brainstorm nouns related to the topic and write a list. A topic of in the office might produce:
and so on.
While the students are doing this, draw several large "bags" on the board and each one is named after a group.
When the time is up, all pens are away and no more writing!
Start with one of the groups (which you can choose at random) and ask them to give you one word on their list. If it's appropriate to the topic then write it in their bag.
Then move on to the next group who must give you a word which must be appropriate and not already on the board. If it's good, write it in their bag on the board.
Then go through all the other groups in turn, asking for a single appropriate and new word to add to a bag.
After a few turns groups will start to run out of words and be frantically thinking new ones up before their turn comes around; they'll also be painful groans as a their new word is given by another team before them.
The winner, of course, is the group with the most words in their bag.
Once the class are familiar with the game you can start to add refinements.