The student is doing a experiment or testing a hypothesis
If we are talking about one single carbon atom, then 4 hydrogen atoms can be bonded to a carbon atom, because there is 4 electrons in the valence shell, and a valence shell needs 8 electrons in total, which causes the carbon to have 4 open bonds. A hydrogen has only one electron in its valence shell of 2, and needs one more to complete it. So, each hydrogen connects to 1 of 4 bonds on the carbon to complete the valence electron.
Fun fact, CH4 is methane.
Aristotle classification
He classified plant and animals into two separate kingdoms
Modern Classification
In this system also, there were two separate kingdoms for plant and animals
