Many of the easiest idioms for kids to pick up on are the ones that use familiar words and images, such as "hot potato" and "piece of cake." Kids may already be aware of idioms because they are so widely used.
An idiom is a saying that often conveys the commonly held wisdom, values and ideas of a society. Because of this, many idioms are locally used within a country, geographical area or community. There are many idioms in common use, although some tend to be more complicated than a kid may be able to understand, such as "sitting on the fence" or "keeping something in mind." Some idioms are so common that kids and adults may use them without realizing they are idioms, such as "hang out" or "pick up."
Some widely used idioms that kids might easily learn include animals: being a guinea pig in a test or being as blind as a bat are both easy to understand give a kid a tangible object to help remember the idiom. There are also many idioms that involve food, such as "flat as a pancake" or "bad apple." Again, these idioms use an image that a kid may already be familiar with to express an idea, and the idioms' visual nature makes them easy to remember.