A very simple energizer which can give a lot of new insights is ‘Clap Clap’. (I love it when it’s more than just an energizer).
The participants stand in a circle. You as the trainer start by making a quarter turn with your body and look at the person which stands left to you. While you are making eye contact with this person you clap in your hands. Ask the other person to clap in his or her hands at the same time. Ask him or her to turn to the person which stands left from him or her and to do the same.
In this way you can make a cycle until everyone has participated.
After this you can do it again and challenge the participants to clap at exactly the same time. This happens best if people make contact with one another.
You can challenge the participants by asking them to do it faster. Or you can ask them to choose between clapping at exactly the same time or not clapping at exactly the same time.