The cell membrane is located under the cell wall. It consists of a different material than the cell wall and is mainly used for the controlled transport of molecules into the cell. It determines the expansion of the cell, maintains the correct ratio of cell components and prevents the cell from leaking. You can imagine it as the skin of an orange that is located under the peel.
Explanation for children:
The cell membrane can be imagined as the inner skin of an orange. It is an additional protective layer under the cell wall. It covers the cell components or the fruit pulp and makes sure that everything stays together. It also ensures that nothing gets into the pulp of the orange in an uncontrolled way.