Complex sentence: For his elementary studies, he attended Gregorio del Pilar Elementary School, where his teachers recognized Sena's artistics skills who tasked him to draw historical figures and had his works posted at the school library.
Split into simpler sentences: For his elementary studies, he attended Gregorio del Pilar Elementary School, where his teachers recognized Sena's artistic skills. They asked him to draw historical figures and posted his works at the school library.