It was while he was helping to mark some of these tests that Piaget noticed that young children consistently gave wrong answers to certain questions.
Ketika ia menolong menandai beberapa contoh dari tes-tes intelegensia inilah Piaget memperhatikan bahwa anak-anak kecil terus-menerus memberikan jawaban yang salah untuk pertanyaan-pertanyaan tertentu.