In a program called nature's notebook, citizen volunteers make and report observations about seasonal changes in plants and animals from year to year—such as flowering, emergence of insects, and migration of birds. this program is an example of

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.