They came out at night, without being called.
They lost at day, without being stolen.
Who are they?

You knock a Table over in the library, and suddenly 20 eyes are looking at you.

Kids with the most attentive eyes can spot a different watermelon in 4 seconds. Can you? Test your eyes now!

If 5 cats catch 5 mice in 5 minutes, how long will it take one cat to catch a mouse?

The Puzzle: A girl, a boy, and a dog start walking down a road.

They start at the same time, from the same point, in the same direction.

The boy walks at 5 km/h, the girl at 6 km/h.

The dog runs from boy to girl and back again with a constant speed of 10 km/h. The dog does not slow down on the turn.
How far does the dog travel in 1 hour?

I am a type of vehicle that has two wheels and is powered by humans. What am I?
Hint 1: You can ride me for exercise.
Hint 2: I am environment-friendly.

During which month do people sleep the least?

The more of this there is, the less you see. What is it?

John had a bag containing colourful marbles. The colours are red, green and blue. The total number of marbles he had in his bag was 60. There are 4 times as many red marbles as green marbles. 6 more blue marbles than green marbles. How many marbles of each colour did John have?

Always in you, Sometimes on you;

If I surround you, I can kill you.

What am I?