1
at a time before people recorded events in writing
Prehistoric
to feel guilty, sorry, or sad about something that one has done
Regret
easy to see
Obvious
an airport official who checks luggage for forbidden objects
Customs agent
to quickly move back and forth in a steady rhythm
Vibrate
support of what is fair, just, and right
Justice
certain to happen in the future
Destined
to look at two or more things and determine how they are the same and different
Compare
Communicate and share experiences
Interact
comes from a foreign place
Exotic
a system of bones that protects the spinal cord
Spinal column
sections of bone that make up the spinal column
Vertebrae
nerve cells
Neurons
visible only through a microscope
Microscopic
describing rock that has transformed due to great pressure and heat
Metamorphic
a force pushing on or against an object
Pressure
a combination of constants and symbols that show a value
Expression
a symbol that represents an unknown number
Variable
a number that does not change
Constant
a property of multiplication that describes multiplying addends by the same factor and then adding the products
Distributive property
spreading of ideas, customs, and traditions
Cultural diffusion
expressions with the same value
Equivalent expressions
put together terms with the same variables
Combine like terms
characteristics
Traits
beliefs and customs that are passed down
Traditions