Why are elements that break apart called unstable?
Note: Give each student a 5×7 index card as he/she enters the classroom. Greeting… “Radiation” (written on the board) When you see or hear this word what do you think about? What do you think it means? I would like you to share your thoughts with me by writing on the card what you thought about when I wrote “radiation” on the board. Do not put your name on the card! [Collect the cards and mix them up. Read several out loud to the class and stimulate discussion on each. Do not attempt to connect any child with a particular note. Write key words from student opinion on the board for future reference.] Introduction Radiation is all around us. It comes from the Earth and from outer space. Many forms of radiation are invisible — we can’t feel it, see it, taste it, or smell it. Yet, it can be detected and measured when present. We measure ionizing radiation in units called millirems. But what is radiation? Radioactive materials are composed of atoms that are unstable. An unstable atom giv