This is an analogy I use in my teachings:
- Function of a nucleus of a cell in a group of cells (tissue).
Office Tower ---> Tissue (group of cells)
1 Office ---> 1 Cell
Table, chair, shelves, computer ---> Organelles in a cell (e.g. ribosomes, mitochondria etc)
Computer ---> Nucleus
Programmes in a computer e.g. Microsoft Word ---> DNA
Protein e.g. eye pigment protein ---> Typed Letter
This Analogy works in all levels of education.