Answer:
According to Piaget, children acquire the mental operations needed to comprehend such things as mathematical transformations and conservation during the concrete operational stage.
Step-by-step explanation:
The stage of concrete operations is part of the theories of cognitive development that the psychological Jean Piaget implemented. The duration of this phase begins from 7 to 11 years and deepens the ability of children to organize their ideas and have rational thinking, that is, their cognitive schemes, especially their logical thinking and solution skills of problems, they are organized into concrete operations. Children during this period must have attained the mathematical notions of classification, seriation, and number; likewise those of conservation of number, liquid and weight or mass. Additionally, at this stage, the notion of volume conservation should be consolidating, which generally occurs towards the end of the period.