What do you think?

Introduce yourselves to each other and discuss in groups:

At the atomic level, humans are made up of mostly carbon, hydrogen, oxygen, and nitrogen. When do you think the carbon atoms in your body got put together (from protons, neutrons, and electrons)?

    A ) within the past day
    B) within the past century
    C) within the past 15 billion years
    D) they have always existed

When called for, hold up the letter of your choice.