Here's a fun ESL first conditional worksheet to help your students learn and practice how to use the first conditional tense.
Give each student a copy of the worksheet. Working alone, students complete first conditional sentences in a story with the correct form of the verbs in brackets. When the students have completed the story, check the answers with the class by eliciting each sentence in turn from a student. Students score one point for each correct sentence. The student with the most points wins.