Simplify the following text for a Grade 4 native English-speaking person.
Original: A seesaw ( also known as a teeter-totter or teeter board ) is a long , narrow board pivoted in the middle so that , as one end goes up , the other goes down .
Simplified: A seesaw ( also known as a teeter-totter ) is a long , narrow board which is fixed in the middle , a little way above the ground . When one end of the seesaw goes up the other goes down .