My child can memorize but can't use it in different situations.

Not being able to use what they memorized in another situation (difficulty with generalization) is common. Learning in one place or one way ties it to that place. Countermeasures: (1) practice the same thing in multiple places, with multiple people and materials, (2) use it in real-life situations, not just the classroom, (3) change conditions little by little. Aim for "usable in life" over "can do it on a test," and matching the same words and steps at home, preschool, and school helps it become usable across situations.