Vocabulary.com is free for students when you sign up for an account. Students will learn vocabulary words they need to know with three different activities: practice, spelling bee, or vocabulary jam.
Discovery Education is a great resource if you're looking to create your own crossword or word search.
Use Quizlet flashcards to learn words that commonly appear in many state standardized tests for 4th grade.
Explore a variety of word games on Arkadium to practice spelling and vocabulary skills.