Paint the walls with a color of your choosing. Use bright colors to encourage mental stimulation, such as yellow or blue. A simple coat of paint is a great way to make a room seem new. To involve the kids, pick a few pre-approved colors, and ask the students to help make a decision through voting, or some other method. Once you're ready to paint, apply the paint to the walls using brushes or rollers. Make sure to put a tarp on the floor to avoid any messes.
Install several dry erase whiteboards and stock up on dry erase markers. The boards are magnetic, and if the boards aren't being used for a lesson, art work and other papers can be attached to the whiteboard. Install the whiteboard at a height where the kids in the classroom will be able to use it also.
Place several large bulletin boards on the walls. These can be used to display students' work, or as a theme board each month. Surround each bulletin board with a decorative border to make the board look almost like a framed photo. The boards serve as a great informational resource as well. Let the kids help decide on a monthly theme to encourage interaction.
Create a mural, if able. If your artistic skills are lacking, ask parents for help. If a mural is not feasible, have the kids make handprints on the walls using washable paint. Each child can write his name under the handprint, along with a favorite bible verse. As more kids join the classroom, more hands can be added.
Have the kids decorate a large plastic tub, or find some other decorative box, and keep it for bibles. Fill the box with the Bibles (try and use kid-friendly Bibles) for use when teaching lessons. Even though many kids bring personal Bibles, these can be used in the case that a child forgets her bible or simply doesn't have one.
Allow the students to assist with any decorating, when possible. If the students are directly involved with the decoration, it will be more likely that they will invite friends. In addition, students will be proud of the decorations and will have a sense of accomplishment. Kids will also be more likely to soak in the information being given, if the learning environment is comfortable.