Student Portal


Investigation 1 – PreLab









Light is all around us. It has the ability to tan or burn our skin. It can be harnessed to melt metals, create electricity, and heat our food. It gives us sight, color, warmth, and enables gadgets like computers, cameras, televisions, traffic lights, mirrors, eyeglasses, and microscopes to function.


Lighting engineers work to reduce our energy use by taking advantage of natural light, sometimes reflecting sunlight off room surfaces to bring light to locations at a distance from windows.


This Investigation is designed to help you to answer the following Focus Question:

  • What is the relationship between the absorption and transmission of light through transparent substances? 

Note: This question is located in your SDR at the beginning and end of the Investigation.


As a class, read the Background(s) in the Investigation. When finished, discuss the following concepts as a class:

  • Scientists use a spectrophotometer to find out exactly how much light is absorbed or transmitted by a liquid.
  • Transmittance is reported as a value between 0 and 100%.
  • 100% indicates that all of the light that is released from the light source is transmitted through the liquid.
  • A value less than 100% indicates that some light is absorbed by the liquid.
  • Absorbance is reported as a value from 0 to 2.0.
  • A reading of 2.0 indicates that all of the light is absorbed by the liquid.
  • A value between 0 and 2.0 indicates that some light is absorbed by the liquid.
  • Scientists use absorbance data to create concentration curves. A concentration curve is a graph of data from a set of samples with known amounts of a substance.
  • Scientists can use a concentration curve to determine the amount of a substance in an unknown sample.




The following list includes Key Terms that are introduced in the Investigation Background(s). They should be used, as appropriate, by teachers and students during everyday classroom discourse.

  • light wave
  • wavelength
  • nanometer
  • absorbance
  • transmittance

Note: Definitions of these terms can be found on the Introduction page to the CELL.

Note: Additional words may be bolded within the Background(s). These words are not Key Terms and are strictly emphasized for exposure at this time.


  • Light is a form of energy that is visible to the human eye. Light has different properties that control how it reacts with its surroundings. Light can be absorbed by matter, transmitted from one place to another, or reflected off of matter.
  • Complete the Recall section in your SDR. 
  • What is light made of?
  • What do you know about light that can help you understand absorption and transmission?
  • Can you name everyday examples of objects that absorb or transmit light?
  • In this first Investigation, you will explore two ways in which light interacts with matter, absorption, and transmission.

Note: You will limit your investigation into the absorption and transmission of light through transparent substances.

  • Play the video below. Remember to follow along with your SDR and make any notes that you think might be helpful in the lab.
  • After the video, divide into your lab groups to discuss strategy for the lab. For example, you may assign certain group members to perform specific functions during the lab.

Note: The purpose of the video is to allow you to anticipate the laboratory experience you will soon encounter. You should leave this PreLab session with a firm idea of what to expect and how to perform in the lab.

Note: Homework is posted below the video.


You should review the Investigation and video in preparation for the Lab.