First two weeks words:

scientific method

hypothesis

control

variable

homeostasis

spontaneous generation

biogenesis

phylogeny

binomial nomenclature

Second two weeks words:

evolution

adaptation

biodiversity

endangered species

SI

volume

mass

weight

kelvin

physical property

Third two weeks words:

chemical change

physical change

condensation

electron

proton

neutron

period

group

Fourth two weeks words:

element

ion

alkali metals

alkaline earth metals

metalloid

noble gases

halogen

chemical bond

compound

molecule