Grammarly
Grammarly Blog: Spelling Plurals With S or Es or Other Plurals
Spelling rules and examples for adding -s or -es to make the plural form of a word.
Roy the Zebra
Roy the Zebra: High Frequency Words Singular or Plural Game 1
Sort words into singulars and plurals to help Lucy the elephant decorate her new home in this interactive game.
ClassFlow
Class Flow: Introduction to Plurals
[Free Registration/Login Required] Created by Robin Duggins, Second grade language arts supplement to lesson and rules for plural words.