Wikipedia sayings about which best characterizes piaget’s formal operation stage?

1.Thought

abstract principles that organize concrete properties, in the stage of formal operations. In recent years, the Piagetian conception of thought was integrated

https://en.wikipedia.org/wiki/Thought

2.Scientific method

Alhacen characterizes the first postulate of Euclid's Optics as 'superfluous and useless' (Book I, [6.54] —thereby overturning Euclid's, Ptolemy's, and Galen's

https://en.wikipedia.org/wiki/Scientific method