If you are in an area with temperate climate, snap a picture of your class in front of a maple tree once a month. They will be able to witness the wonder of nature as the buds bloom and grow and how different the tree looks with each change of season. Talk about things people can obtain from a maple tree such as furniture, flooring and maple syrup and what would happen if people couldn't get these things.
Take the children on a field trip to a pond, park, forest or simply on a tour of your school grounds. Record their observations about the plants, animals and other resources they see. Point out how the plants and animals interact and are an ecosystem. Gather specimens such as leaves of different shapes, small rocks, pine cones and acorns. Take pictures of trees, small plants and animals you see on your excursion. Carry the items back to class, discuss their importance, classify them, and select several to make a "nature book" for the classroom.
Plant seeds in the classroom and let the children record weekly growth. Ask them what they think the results will be if the plant doesn't get enough sun or water and conduct those experiments.
If you have the facilities to do so, keep a small mammal pet, such as a rabbit, in the classroom and have the class observe how the animal grows and changes over time. Allow each child to have a turn caring for and feeding the pet. Read about and discuss the importance of the animal and other interesting things about it such as how it survives in its natural habitat.
Allow the children to use their senses to learn about a variety of natural resources. Bring a recording of bird calls to class and see how many children can identify them after you play it a few times.
Have your class look at a drop of pond or lake water, a tiny piece of a leaf, a particle of soil and other natural items under a microscope.
Ask the children to bring a selection of fruits and vegetables in a lunch box from home. Blindfold each child by turn and see if he can identify the items in his box by taste.
Encourage your class to touch and smell items such as flower petals; the classroom pet (if you have one); mint leaves; a chestnut; pine needles and other leaves, fruits and vegetables; a peacock or other large bird feather; a piece of tree bark; and sticky burrs. Use the opportunity to instruct them about their responsibility to protect and conserve natural resources.