Concentration.

Hmm.. This is about something what my teacher taught me. It's a way to find out whether someone's concentration, focus and dexterity levels are high enough. Though it is easier to do it practically, I'll explain by theory.

Start off by asking your friend to raise his right hand up and point the index finger upwards. Make sure that you and him/her are focused on one another and can see what the other is doing as this will most definitely trick him/her into making a mistake in the end. You'll know what mistake it is later. Now, you too raise your index finger upwards with your hand straight up in the air. Okay, now, you tell your friend to point to his/her finger onto his hair, neck, lips, nose, ear and any other parts, leading him with your finger and moving at a steady pace to a rapid pace. Now, the tricky part. When you feel the pace is fast enough and you think he/she is really following your finger to where it is pointing, you just have to mention one part such as the "chin" BUT point your finger to your cheek. If your friend followed your gesture and pointed to the cheek, it meant he/she did not follow the instruction clearly. This means his/her concentration is not very good. However, if your friend points to the chin, well, let's just say he has been listening closely and has not been following your gestures. That proves that he/she has attained a high level of dexterity.

Have fun. =.=". Seriously, I was caught making that mistake... lol ...