Elementary School Lessons

1. A set is a group of objects put together.
2. The objects in a set are called elements.
3. An empty set is a set with no objects or elements.

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1. Equivalent sets are sets that have the same number of elements.
2. Equivalent also means as many as.
3. Non-equivalent sets are sets that have different numbers of elements.

Lesson 10

You Hear sounds

Sound is produced by the rapid back-and-forth movement of an object. Sound may be pleasant or unpleasant.