In this thread we are going to enrich our vocabulary in an interesting way. All you have to do is to add a group of words or expressions; about 4, 5 or 6 items in a group, one of these items doesn’t belong to others or doesn't fit them easily. What you need to do first is to pick up the odd item then state your reason and add a new group.
Example:
Which of the following is the odd one out?
A.
1. Human
2. Dolphin
3. Shark
4. Whale
Human is the odd one out. The others are sea animals.
B.
1. Sit down
2. Take the weight off your feet
3. Stand up
4. Put your feet up
Stand up is the odd one out. The others are all to do with sitting down and relaxing.
Let's start now
Which of the following is the odd one out?
1. Women
2. Men
3. Mice
4. Children
5. Teeth
6. Apples
How come I didn't notice the singular and plural thing. 
but I suggest to have more difficult words 
it will be motivating for all of us