Free Spanish worksheets: SER O ESTAR. For some of these, either ser or estar would work depending on the context of use. You could have kids write a note about how the message changes based on which verb is used. https://es.islcollective.com/resources/printables/worksheets_doc_docx/ser_o_estar/ser-y-estar/67735
Study Spanish is a website that is dedicated to making it easy to learn how to speak Spanish. It offers 1000's of lessons that are sure to make even advanced students more fluent speakers of the language. Study Spanish also has a focus on grammar, vocabulary, and verb conjugation drills. This robust site offers a lot of free content and is great for students of all ages.