If children cannot grasp the concept of conservation, they are unable to:

Step 1: Define the Problem

Identify what is meant by "the concept of conservation" in the context of child development.

Step 2: Break Down the Problem

• Understand the developmental stage related to the concept of conservation.
• Determine what abilities or understandings are lacking if a child cannot grasp this concept.

Step 3: Apply Relevant Concepts

• The concept of conservation is part of Jean Piaget's theory of cognitive development.
• It refers to a child's ability to understand that certain properties of objects, such as volume, mass, or number, remain the same despite changes in the form or arrangement of the objects.

Step 4: Analysis, Verify and Summarize

• If children cannot grasp the concept of conservation, they are typically in the preoperational stage of Piaget's developmental stages, which occurs between ages 2 and 7.
• At this stage, children may struggle with understanding that quantity does not change even when its appearance does (e.g., water poured into a differently shaped glass).

Final Answer

If children cannot grasp the concept of conservation, they are unable to understand that certain properties of objects remain constant despite changes in their form or arrangement.