For an easy, quick way to decorate the classroom for kindergarten through third grade, when children are still learning plants, use pictures of flowers. Print out a photograph of each flower and laminate it. Punch a hole at the top of each sheet and string the whole collection along a length of ribbon to create a garland. Hang the garland along one wall of the classroom at a height that students can see easily and include a description on the back that talks about the flower and the places it grows. Choose a theme, like tropical flowers or flowers that are local to gardens in your town. When children see the flowers in the community, the children will be able to recognize the type.
Miniature gardens can be decorative as well as educational. Set out flower boxes and have your students create miniature gardens. Pass out seeds and choose plants that will be able to grow in the amount of light that comes in through the windows. The project will teach kids about gardening and selecting the right type of plant for your conditions. When the plants bloom, it will brighten up the room and the students will be able to celebrate. This type of project is best for older children in fourth grade through sixth grade, who will be responsible in taking care of the gardens.
Lawn gnomes are a standby in many gardens. Bring the gnomes into the classroom to spruce things up and delight your students. Test your students' observation skills by hiding gnomes in new places each week or allow the gnomes to sit by the desk of the student of the week, for example. You can also use them in the curriculum by naming them and having the kids write stories about them. Depending on your students, gnomes make a fun decoration for classes up to sixth grade.
Bring garden implements into the classroom by using plant stakes in your decor. Use them to reinforce a concept: write words you are learning or the names of places from your geography lesson. Garden stakes can be used in a bulletin board at the beginning of the year if you write one student's name on each one and "plant" the stakes. Plant stakes are best for younger classes up to third grade.