Here's a dandy worksheet on verbs and simple past tense. Students practice cojugating the verbs by adding -d or -ed. Then they practice turning simple present tense sentences into simple past tense.
Based on the readability scores for this text, Past Tense Verbs Worksheet is recommended for students reading at grade levels 1 - 5. This text should be accessible to any student reading at a 1st grade reading level or higher.