Sitting quietly and discussing a problem on the board might work well for mastering mathematics, but when it comes to developing language skills, it's a good idea to have your students interact with each other. Try singing a song like "Simon Says" or playing a game like "Telephone" in which one student gives an order (imperative sentence) that the rest must act out. Before the game starts, give them an example to follow, such as "Ms. Clarke says, "Stand on your head." Explain that an imperative sentence usually gives a command or makes a request. Have one student give the others similar imperative commands, and soon you'll have the students laughing and learning at the same time.
Children and particularly teens love competition. To help encourage mastery of sentence types, split your students into two groups (boys vs. girls, A-M last names vs. N-Z last names, for example. Have them name their teams, and put up a scoreboard. Next, have the two teams square off. Give the two teams a sentence ("Michelle hit seven home runs last week!" "Jeff wanted to know, 'How much was the backpack?'") and ask one person from each team to identify the sentence type -- declarative, imperative, interrogative or exclamatory. Keep track of the score, and when the students feel confident, allow a representative from each team to make up a sentence and challenge the other. The students will master the concepts even more quickly if there is a prize on the line, so offer small treats, extra recess time or a homemade trophy as a reward to the team with the highest score.
Tie the types of sentences to something the students are familiar with and can identify with. For example, play a Disney movie in class and pause the tape after a song or a line of dialogue, and ask the students to identify which type of sentence their favorite character was using. For older children, try playing a clip of a favorite celebrity or sports hero being interviewed. Ask them how often the different sentence types were used.
Teaching can be a challenging task, and often the hours spent grading papers, preparing for lessons and designing worksheets can be monotonous. By having fun yourself, you'll help encourage your students to master the lesson material quickly. Design a worksheet that offers an example of your artistic ability. Write a play about characters using different types of sentences, and have your students play the different parts. Write a song about sentence types and perform it for your class. "Grow" a paper flower garden in your classroom by having your students identify one of the four sentence types to make petals for the flowers.