Directions: Identify whether such changes in the materials are useful or harmful to the environment by putting a check mark () on the proper column. Changes in the materials Effect of the changes in the materials to the environment Useful Harmful 1. Burning of garbage such as plastic materials, rubber and other wastes 2. SR's 3. Cutting of fabric to be made into clothes. 4.Changing wood into charcoal for cooking 5. Throwing the trash into the river or sea.​