Group 1: For most nouns, add S
student - students apple - apples
Group 2: For nouns ending in -X, -S, -Z, -CH, and -SH, add ES
box - boxes dress - dresses
Group 3: For nouns ending in a consonant + Y, change Y to I and add ES
party - parties galaxy - galaxies
Group 4: For nouns ending in a vowel + Y, add S
boy - boys key - keys
Group 5: For most nouns that end in F or FE,F or FE becomes VES
elf - elves loaf - loaves
Group 6: For most nouns that end in O, add S
kangaroo - kangaroos piano - pianos
Group 7: For certain nouns that end in a consonant + O, add ES
hero - heroes potato - potatoes