What is intelligence? What is it that some have lot of and others little? Controversial issue whether it is a single thing.

Intelligence is an ability to gather, synthesize, analyze, retain, and reproduce information. In other words, an ability to learn.

There is NOT one definition because intelligence is a composite of abilities fused into one paradigm which is what each theorist would identify as intelligence on their own.

Among theorists of intelligence there are:

Erick Erickson

Jean Piaget

Karl Brunner

Howard Gardner (multiple intelligences)

Albert Bandura (social learning)

Stephen Krashen (affective filter)

Bloom (taxonomy of learning)

etc etc etc

The reason some students know more than others may be attributed to:

genetic factors/ psychosocial development/ psychological development/ support systems/ feasibility to attain information/asynchronous development.

For more information, on how some have higher IQ's than others, check the link provided.