Here is a 2-page handout that provides 3 major rules for pluralization. Students pluralize over 50 words and cite the rule determining its proper pluralization.
Rule 1: Most singular nouns add –s to make them plural.
Rule 2: If a singular noun ends in a consonant and a y, change the y to I and add –es.
Rule 3: If a singular noun ends in s, ss, x, ch, or sh, add –es to make it plural.