Simplify the following text for a Grade 8 native English-speaking person.
Original: Hadrons , along with the valence quarks that contribute to their quantum numbers , contain virtual quarkâ `` antiquark pairs known as sea quarks .
Simplified: Quarks that make the quantum number of hadrons are named ` valence quarks ' . The two families of hadrons are baryons ( made of three valence quarks ) and mesons ( which are made from a quark and an antiquark ) .