(no longer active)

“A man is writing his will and he wants to leave everything he has to one of his two sons, whichever one is more dedicated. To decide which one will win his fortune he gives them each a car and tells them that whoever's car passes the finish line he has set up last will get everything he has. After a month of both sons refusing to cross the line they finally go to their uncle for advice. They both leave their uncles house in a hurry and race to the finish line as fast as they can. What advice did their uncle give?”
― M. Prefontaine, Difficult Riddles For Smart Kids: 300 Difficult Riddles And Brain Teasers Families Will Love

“This is an unusual paragraph. I'm curious as to just how quickly you can find out what is so unusual about it. It looks so ordinary and plain that you would think nothing was wrong with it. In fact, nothing is wrong with it! It is highly unusual though. Study it and think about it, but you still may not find anything odd. But if you work at it a bit, you might find out. Try to do so without any coaching.”
― M. Prefontaine, Difficult Riddles For Smart Kids: 300 Difficult Riddles And Brain Teasers Families Will Love

“John is 10 years old in 1870, but only 5 years old in 1875. How is this?”
― M. Prefontaine, Difficult Riddles For Smart Kids: 300 Difficult Riddles And Brain Teasers Families Will Love

“B, C, D, E, G, P What is the next letter in the sequence?”
― Puzzleland, 30 Interactive Brainteasers to Warm up your Brain