Start a classroom community outreach project by explaining to your elementary school students that helping those in need is part of bettering the community. It's a good idea to start the project when there isn't a holiday coming up, as this is usually when schools host canned good or clothing drives to give to those in need---children should understand that community building should be a year-round activity. Activities can include planting a garden on school property with your students, and teaching them about which fruits and vegetables grow best in particular seasons. When the plants are ripe, pick them with your students and give them to a community center or food bank. Older elementary school students may also be interested in going to different places in the community and planting gardens to promote health around the city.
Break the class into groups, and give each group a responsibility in the classroom "community." For instance, make one group in charge of feeding the class pet each day, and assign the task of cleaning up the classroom after playtime to another group. Encourage the children to work together within their groups to assign roles or take turns performing small duties that will help accomplish the overall group goal. Explain that in a community, small groups, like families, educators, and government officials, have to talk amongst themselves to determine the best contributions to make to the community at large, and that groups in the community have to work together so that the neighborhood or city can benefit.
Inform your students of community hardship or tragedy that is taking place locally or in another part of the world, and work with the children to come up with ways that the class can help. For instance, if you learn on the local news that a family has experienced a house fire recently, inform the students' parents of your intent to collect items like clothing, food and gasoline gift cards that will make the victims' lives a little easier while they repair their home. Arrange a time to drop these items off with the family, and help your students write a short note expressing their hopes that their contribution will be helpful. You can also get your students involved in world events by sharing stories about areas that have been affected by famine or natural disasters. Bring a large box to the classroom, and let the students fill it with things they feel the victims may find useful, like non-perishable foods or teddy bears. Then, create a di with the names of the countries you've been talking about in class, so the students can roll it and decide where the box will go.
Assign a community occupation to each of the children in your class, so that they can research the person's job responsibilities and the benefit they bring the community. For instance, allow one child to research the job of police officers, have another child learn all about a firefighter's typical day, and give another student the responsibility of learning what a teacher or librarian's job entails. Devote a week or so to this lesson, so that you can ask adults who hold these jobs to come visit the class and provide students will real-life stories concerning their community roles.