1. Cell theory

2. Robert Hooke and the Cell
In the 1660s, Robert Hooke began using microscopes to look at cork, which is part of a cork oak tree’s bark
The openings reminded him of the small rooms, called cells, where monks lived

3. Plant and animal Cells
Matthias Schleiden, a German scientist, looked at plant cells
Theodor Schwann, another German scientist, looked at animal cells
Almost 2 decades later, Rudolf Virchow, a German doctor combines all of the observations made by the 3 scientists into a theory

4. Cell theory All living things are made of one or more cells
The cell is the smallest unit of life
All new cells come from preexisting cells