Big Ideas

from the American Association for the Advancement of Science:

Benchmarks for Science Literacy


Atomic Structure:
  • All matter is made up of atoms, which are far too small to see directly through a microscope.  The atoms of any element are alike but are different from atoms of other elements.  Atoms may stick together in  well-defined molecules or may be packed together in large arrays.  Different arrangements of atoms into groups compose all substances.
  • Atoms and molecules are perpetually in motion.  
  • There are groups of elements that have similar properties, including highly reactive metals, less-reactive metals, highly reactive nonmetals) such as chlorine, fluorine, and oxygen), and some almost completely non-reactive gases (such as helium and neon).
  • No matter how substances within a closed system interact with one another, or how they combine or break apart, the total weight of the system remains the same.  The idea of atoms explains the conservation of matter:  If the number of atoms stays the same no matter how they are rearranged, then their total mass stays the same.
  • Models are often used to think about processes that happen too slowly, too quickly, or on too small a scale to observe directly, or that are too vast to be changed deliberately, or that are potentially dangerous.
  • Different models can be used to represent the same thing.  What kind of a model to use and how complex it should be depends on its purpose.  The usefulness of a model may be limited if it is too simple or if it is needlessly complicated.  Choosing a useful model is one of the instances in which intuition and creativity come into play in science, mathematics, and engineering.
Periodic Table:
  • Elements are arranged on the periodic table based on the number and location of their subatomic particles.
  • Elements are arranged on the periodic table according to increasing atomic number.
  • Elements behave differently based on the location of their subatomic particles.
  • Elements in the same family exhibit similar properties.
  • The periodic table is based on the premise of periodicity (i.e. repeating patterns).


Scientific Inquiry/Experimental Design:
  • Scientists differ greatly in what phenomena they study and how they go about their work. Although there is no fixed set of steps that all scientists follow, scientific investigations usually involve the collection of relevant evidence, the use of logical reasoning, and the application of imagination in devising hypotheses and explanations to make sense of the collected evidence.
  • If more than one variable changes at the same time in an experiment, the outcome of the experiment may not be clearly attributable to any one of the variables. It may not always be possible to prevent outside variables from influencing the outcome of an investigation (or even to identify all of the variables), but collaboration among investigators can often lead to research designs that are able to deal with such situations.
  • What people expect to observe often affects what they actually do observe. Strong beliefs about what should happen in particular circumstances can prevent them from detecting other results. Scientists know about this danger to objectivity and take steps to try and avoid it when designing investigations and examining data. One safeguard is to have different investigators conduct independent studies of the same questions.
  • New ideas in science sometimes spring from unexpected findings, and they usually lead to new investigations.