A cell is like a school...
The walls of the school building is like the cell membrane because it keeps all the contents in the school like the cell membrane keeps all the contents of the cell inside of it.
The teachers and principle of the school are like the nucleus of the cell. They give orders and control who goes in and out of the school, just like the nucleus in a cell.
The school students are like the cytoplasm. They are scattered throughout the majority of the school just like the cytoplasm is scattered throughout the cell.
The school computers are like the nucleoid of a cell because they store information from the students like the nucleoid stores DNA in a cell.
The cafeteria is like the ribosomes of a cell. It creates protein and food that the students need just like the ribosomes create proteins that the cell needs.