=======Reviewing Powerful Ideas=======
We began class today by reviewing where we have been and where we are headed with class. We reviewed the powerful ideas we have learned so far:\\
  * Light rays leave a source in all directions\\
  * Light rays travel in straight lines\\
  * Light rays bounce off smooth objects like mirrors in a regular way (angle of incidence = angle of reflection)\\
  * Light rays bounce off rough objects in all directions\\
  * For someone to see an object, light rays must enter the eye\\
  * Light rays form the sides of similar triangles in pinhole cameras: H/D = h/d\\
  * Objects left for a long time in a room reach the same temperature, room temperature\\
  * Materials conduct heat and energy at different rates\\
  * Heat flows from a heat source to colder objects\\
  * Hot and cold water, when mixed together, come to a common temperature in between the hot temperature and the cold temperature; that is called the equilibrium temperature\\
  * Change in temperature will be smaller for a bigger amount of water\\
  * Change in temperature will be bigger for smaller amount of water\\
  * Conservation of energy: heat lost = heat gained\\
  * Heat energy lost by hot water: (mass of hot water)(T change of hot water)(c of water)\\
  * Heat energy gained by cold water: (mass of cold water)(T change of cold water)(c of water)\\
  * c is a property of materials called specific heat. Specific heat is the amount of heat energy needed to raise the temperature of one gram of the material by one degree Celsius. 
  * Water is a standard: c = 1 calorie is needed to raise the temperature of 1 gram of water (at 1 atmosphere of air pressure) by 1 degree Celsius