★ individual は「人」だけではない

Cambridge Advanced Learner's Dictionary の定義
noun[c]1.
a single person or thing especially when compared to the group or set to which they belong

Merriam-Webster's Advanced Learner's English Dictionary の定義
noun[count] 3.
a single member or part of a group

e.g.)The markings on tigers are unique to each individual.
（＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿。)

Optimized studying based on the forgetting curve vastly improves memorization. - What is reminDO?

Memorize