These are from test papers and essays submitted to science and health teachers by junior high, high school, and college students around the world. 

"When you breath, you inspire. When you do not breath, you expire."

"H2O is hot water, and CO2 is cold water"

"To collect fumes of sulphur, hold a deacon over a flame in a test tube"

"When you smell an oderless gas, it is probably carbon monoxide"

"Nitrogen is not found in Ireland because it is not found in a free state"

"Water is composed of two gins, Oxygin and Hydrogin. Oxygin is pure gin. Hydrogin is gin and water."

"Three kinds of blood vessels are arteries, vanes and caterpillars."

"Blood flows down one leg and up the other."

"Respiration is composed of two acts, first inspiration, and then expectoration."

"The moon is a planet just like the earth, only it is even deader."

"Artifical insemination is when the farmer does it to the cow instead of the bull."

"Dew is formed on leaves when the sun shines down on them and makes them perspire."

"A super-saturated solution is one that holds more than it can hold."

"Mushrooms always grow in damp places and so they look like umbrellas."

"The body consists of three parts- the brainium, the borax and the abominable cavity. The brainium contains the brain, the borax contains the heart and lungs, and the abominable cavity contains the bowls, of which there are five - a, e, i, o, and u."

"The pistol of a flower is its only protections against insects."

"The alimentary canal is located in the northern part of Indiana."

"The skeleton is what is left after the insides have been taken out and the outsides have ben taken off. The purpose of the skeleton is something to hitch meat to."

"A permanent set of teeth consists of eight canines, eight cuspids, two molars, and eight cuspidors."

"The tides are a fight between the Earth and moon. All water tends towards the moon, because there is no water in the moon, and nature abhors a vacuum. I forget where the sun joins in this fight."

"A fossil is an extinct animal. The older it is, the more extinct it is."

"Many women belive that an alcoholic binge will have no ill effects on the unborn fetus, but that is a large misconception."

"Equator: A managerie lion running around the Earth through Africa."

"Germinate: To become a naturalized German."

"Liter: A nest of young puppies."

"Magnet: Something you find crawling all over a dead cat."

"Momentum: What you give a person when they are going away."

"Planet: A body of Earth surrounded by sky."

"Rhubarb: A kind of celery gone bloodshot."

"Vacumm: A large, empty space where the pope lives."

"Before giving a blood transfusion, find out if the blood is affirmative or negative."

"To remove dust from the eye, pull the eye down over the nose."

"For a nosebleed: Put the nose much lower then the body until the heart stops."

"For drowning: Climb on top of the person and move up and down to make artifical perspiration."

"For fainting: Rub the person's chest or, if a lady, rub her arm above the hand instead. Or put the head between the knees of the nearest medical doctor."

"For dog bite: put the dog away for sevral days. If he has not recovered, then kill it."

"For asphyxiation: Apply artificial respiration until the patient is dead."

"To prevent contraception: wear a condominium."

"For head cold: use an agonizer to spray the nose until it drops in your throat."

"To keep milk from turning sour: Keep it in the cow."