The Middle School Science curriculum is the link between elementary concepts and the more in-depth concepts of the high school curriculum. This curriculum covers the Earth and Space Science topics of energy conservation and natural resources, weather, the rock cycle, earthquakes, volcanism, seasons, moon phases, eclipses, and the energy of the sun. The Life Science topics that are covered in middle school include: reproductive biology and life cycles, cell division, plant reproduction, population dynamics, specific ecosystems and the interactions within, food webs and energy pyramids, natural selection, introduction to genetics, and exploration of microscopic organisms. The Physical Science curriculum for this level has two components: Chemistry and Physics. The chemistry topics include study of the structure and behavior of matter, transformations of matter, such as, phase change, dissolution, reaction, elements, atomic structure, molecules, compounds, and energy transfers. The physics topics include the study of energy and the different forms it can take, how forces do work to change energy from one form to another, how machines reduce the effort force needed to do work, and how forces change the motion of objects.