Baseball Card Collecting

Looking for a new hobby? Do you like baseball? If you answered "yes" to these two questions baseball card collecting might be a fun pastime for you to begin! Ever since candy and gum manufacturers started putting cards with pictures of popular baseball players into the packages in the 1800’s to encourage young people to buy their sweets, kids have been collecting baseball cards. Now, more than 200 years later, baseball card collecting has become a popular hobby for children and adults alike.

Based on this paragraph, what can you infer "sweets" are?