1 Why don't sleeping birds fall from the tree?
Birds have a kind of automatic grip, similar to a clothespin. They owe this to the tendons in their legs. When they crouch down, the toes and claws contract due to the tighter tension of the tendons. This grip is so tight that it takes birds a lot of strength to take to the skies again after a nap.

2 Why is a marathon course exactly 42.195 kilometers long?
This goes back to a legend according to which a running messenger delivered a message from the city of Marathon to Athens, a distance of around 40 kilometers. The current length was determined in London in 1908 at the request of Queen Alexandra.

3 What should I do in the event of a wrong-way driver?
Do not overtake as soon as you have the message that someone is traveling in the wrong direction on your route. Stay in the right-hand lane so that the wrong-way driver can get out of the way in the left-hand lane. Slow down and switch on your hazard warning lights. This way you will be seen more quickly and can take evasive action more easily. If you are unsure, you should leave the road at the next opportunity and wait until the traffic radio gives the all-clear.

4 Where do the pilot and crew sleep on the plane?
There are actually rest areas on board large aircraft where the crew can stretch their legs. The quarters are so well "hidden" that passengers do not get to see them. The sleeping quarters for pilots are either directly behind the cockpit or at the front above the passenger cabins. A small ladder then leads to the sleeping area, which usually has space for one or two bunks. The sleeping quarters for the rest of the crew are located at the very back of the aircraft, in the middle above the cabin or below in the cargo hold - this varies greatly depending on the aircraft. There are usually double bunk beds here, where up to ten people can rest at the same time.

5 How do I give first aid in five minutes?
Place the unconscious person in the recovery position. Make an emergency call to 112. If breathing has stopped, give chest compressions: press on the chest with the ball of your hand. Position it so that the center of the hand is in the middle of the sternum. Press 30 times and then give two breaths through the nose, keeping the mouth closed. Do not bandage any bleeding, but cover it with a sterile dressing and apply pressure to the wound.

6 Why is flying so strenuous?
It's because of the air pressure. It's as low as if you were sitting on a 2,500 meter high mountain. The dry air also makes you feel limp. The legs also suffer because the blood no longer circulates properly and builds up. As a result, the body releases stress hormones, which weaken the immune system.

7 Why shouldn't tomatoes be refrigerated?
The reason is simple: because the red delicacy then completely loses its flavor. US researchers found that tomatoes stored in the fridge lost 68 percent of their flavor after just four days. It is best to store them in a shady place between 12 and 16 degrees.

8 Where does the stomach growl come from?
Day and night, our stomach and intestines contract and expand without stopping - even if we haven't eaten anything. This keeps the digestive tract clean and tidy, so to speak. Food is broken down and transported further. If we have not eaten anything solid for a long time, the stomach is not empty, but still contains a lot of air and liquid. When the stomach walls contract, they start to vibrate - similar to a bagpipe. The result is the typical humming sound.

9 Why do some people have freckles?
Where exactly the cute dots come from is not yet fully understood. Some researchers suspect that it is due to the MC1R gene, which controls melanin production in the body. Melanin is the pigment that gives our skin such a wonderful tan. Freckles are nothing more than pigment spots that contain more melanin than the rest of the skin. Incidentally, the pigments are stimulated by UV radiation, i.e. when the sun shines on them. This is why freckles on the face and body usually only sprout when the weather is at its best.

10 Why are only 100 ml allowed on board?
This regulation has to do with planned terrorist attacks in London in 2006. Attackers wanted to blow up several airplanes with liquid explosives hidden in drinks bottles. Fortunately, this was prevented. However, it was then decided to restrict the amount of liquids that could be carried in hand luggage. A total of one liter, divided into several containers with a maximum capacity of 100 ml, may be carried on board. This quantity has been determined by security experts.

11 Why do you pay differently with a card?
Sometimes with a PIN, sometimes with a signature. If you shop with a debit card, you may wonder why the transaction is always completed differently. This depends on a random system or on the customer's ability to pay. The reason: if you pay with a PIN, the account is debited immediately. This is more secure for the retailer, but they have to pay 0.2 percent of the purchase price to the banks. If you put your signature on a receipt, you give the retailer direct debit authorization. The amount is only deducted from the customer's account later.

12 Where do the old clothes end up?
90 percent of the donations go to recycling companies that trade in the clothes and make a profit. In the case of reputable collectors (e.g. the German Red Cross), the donations go to charitable organizations. So pay close attention to the provider.

13 How do you form a rescue lane?
It is intended for vehicles with flashing blue lights that need to get to the scene of an accident as quickly as possible. All drivers are obliged to clear the emergency lane. On two-lane roads, it is formed in the middle of both lanes; on three-lane roads, it is formed between the left and middle lanes. Drivers in the left-hand lane therefore move to the left. If you are driving in one of the other lanes, you drive to the right.

14 How do traffic jams actually occur?
Accidents, roadworks and lane narrowing are three triggers for the annoying stop-and-go. However, the main cause is simply road congestion. This is why traffic jams often form during travel and rush hour. There are simply too many cars on the road with excessive speed differences and, as a result, too many cars tailgating.

15 Why are there always four passport photos?
This goes back to the good old Polaroid passport photo camera. It came onto the market in 1970 and had four lenses. Accordingly, it took four portraits on one self-developing print. The technology progressed towards digital, but the standard remained. People are creatures of habit.