Instructions
Examine the date. From 1856 to 1858 and in 1943, the U.S. mint made pennies that had the appearance of silver but were really manufactured with other metals. The 19th century flying eagle penny was 88 percent copper and 12 percent nickel, while the 1943 wartime penny was made out of steel. Also make sure that the penny is 1966 or older, because 1966 was the year the U.S. Mint stopped minting silver coins for circulation.
Look at the coin's appearance and size. A silver penny might be a "transitional error" that was struck on metal meant for a silver dime instead. Compare the penny to a dime minted by the U.S. to see if it is the same size. This will work with any U.S. dime because its size has always remained the same. Also check to see if the entire design of the penny is visible. A penny is significantly larger so its design will not fit on the metal meant for a dime. This is called "out-of-round."
Feel the coin and apply the "ring test." It may have at one time been subject to a science test or silver-plated. This will leave the coin with a greasy covering that can be felt by rubbing your thumb gently across the surface of the coin. Finally, deliver the "ring test" by dropping the coin onto a table and listening for the sound of a metallic ring. Compare it to a regular penny which will deliver only a dull thud.