Simplify the following text for a Grade 8 native English-speaking person.
Original: Polgar and her two younger sisters , Grandmaster Judit and International Master Sofia , were part of an educational experiment carried out by their father LÃ szlÃ PolgÃ r , who sought to prove that children could make exceptional achievements if trained in a specialist subject from a very early age .
Simplified: Polgar and her two younger sisters , Judit and Sofia , were part of an educational experiment carried out by their father LÃ szlÃ PolgÃ r. He and his wife Klara educated their three daughters at home , with chess as the specialist subject .