Consumers often spend a few puzzled moments looking at egg cartons in supermarkets. That's because there are six official egg sizes. The sizes are determined by weight. A jumbo,the largest-size egg, weighs 30 ounces while a peewee egg, the smallest size, weight only 15 ounces.In between are extra-large, large, medium, and small eggs. Most markets only stock the four largest sizes; small and peewee egg are usually sold to bakers and companies in the food processing business. People take cars and other road vehicles for granted today. However, the idea of such vehicles was unheard of about 500 years ago. Then, in 1478,the artist and inventor Leonardo da Vinci designed a self-propelled vehicle. His drawing showed a boxy, open-topped wooden machine with three wheels. Coiled springs would make the vehicle have been made in recent years and are on exhibit in museums in Italy.