PROJECT BASED LEARNING SCIENCE: Bats With Digital Slides and STEM Activity - Bats are important to our ecosystems. Without bats, our ecosystems will not work. Because bats have such a unique sensory abilities, they can also be studied to learn more about diseases that effect us, like blindness and deafness. This project based learning unit involves 21st Century Learning, science, research, writing, making a video, and STEM. A great PBL unit for your 3rd, 4th, and 5th grade students!