Before you read a story to the students ask them to listen carefully so that they can tell you the beginning, the middle and the end of the story. As you read the story, stop and talk about it with the students so that they may recall the events more clearly. When you finish, ask the students what happened first, and explain this is the beginning of the story. Ask them what happened next, and so forth. The language you use when talking to them should help to illustrate what happens first is the beginning, what happens next is the middle, and what happens after that is the end.
Teacher Vision has an example lesson plan for the story, "The Very Hungry Caterpillar," by Eric Carle.
After the students hear the story read aloud by you, ask them to write in their reading journals about the story and to identify the sequencing as in the beginning, the middle and the end. Ask them to write what happened in order. Using the example of "The Very Hungry Caterpillar," by Eric Carle, they would write about the sequence the caterpillar undergoes and how it becomes a butterfly.
The Education place has a free printable graphic organizer that further illustrates the concept of sequencing by using three blocks in which children write down the sequence of events. The top is the beginning, the middle is still the middle, the bottom represents the end. This approach uses a cross mix of words that mean the same thing.
Read a story aloud to the students and then mix up the sequence by listing the beginning, middle and end sections out of order. You can do this on the board where the children come to write what happened first, second, and so forth, or you can copy the story on paper with the sequences out of order. Educational sites such as DLTK have story sequencing puzzles that you can print for free.