"Jean Piaget e ne e le seruti sa moSwiss seo se simolotseng dithuto tsa kgolo ya tlhaloganyo mengwageng ya bo 1920. Dikgatlhego tsa ga Piaget tsa ntlha e ne e le tseo di dirang ka ditsela/mekgwa eo diphoofolo/diphologolo di tlwaelang ditikologo tsa tsona ka teng mme dikwalo tsa gagwe tsa matlhale tsa ntlha ka serutwa se di ne tsa phatlhalatswa fa a le mengwaga e e lesome. Tiragalo e e ne ya mo rotloetsa go latela Ph.D. ya Zoology, eo e neng ya mo isa kwa kgatlhegong ya gagwe ya bobedi mo go epistemology. Epistemology e entsha lefata go tloga go philosophy mme e dira ka tlhogo ya kitso. Piaget o ne a dumela/kgolwa gore tlhago ya kitso e tswa mo go Psychology, ka jalo o ile a ya Paris mme a simolola go dira diteko tsa ntlha tsa “standardized intelligence test” kwa Alfred Binet laboratories; se se ne sa huetsa tsela-tiro ya gagwe segolo. Fa a ntse a tsweletsa diteko tsa tlhaloganyo a simolola go godisa kgatlhego e e itlhokoditseng ya ka moo go tlhaloganya ga bana go diregang ka teng. Ka ntlha e, o ne a aga laboratory ya gagwe mme a nna mengwa a kwala ka ka moo go tlhaloganya ga ngwana go golang ka teng a ba a leka go fitlhelela ka moo bana ba golang ka teng go ya ka dikgato tse di farologaneng tsa go akanya/tlhaloganya/nagana. Se se dirile gore Piaget a tlhagise dikgato tse nne tsa botlhokwa tsa kgolo ya go tlhaloganya: sensorimotor stage (tsalo go fitlha go ngwaga wa bobedi), preoperational stage (age 2 to 7), concrete-operational stage (ages 7 to 12), and formal-operational stage (ages 11 to 12, and thereafter)."