Unit Overview
6.1 Light & Matter

Why do we sometimes see different things when looking at the same object?

Unit Summary

How does a one-way mirror work? Though most everyone knows that one-way mirrors exist, having students model how they work turns out to be a very effective way to develop their thinking about how visible light travels and how we see images. Initial student models reveal a wide variety of ideas and explanations that motivate the unit investigations that help students figure out what is going on and lead them to a deeper understanding of the world around them.

A video of an experience with a one-way mirror, gets students to organize and write down their initial ideas and then they dig in to test those ideas and figure out what is really happening. Students build a scaled box model of what they saw in the video to test out their ideas. Using two boxes combined together with a one-way mirror in between the two, students vary the presence of light in the two boxes to figure out how a one-way mirror works and improve their initial models so they accurately explain how light is reflected and transmitted through materials and the basics of how these behaviors of light result in the images we see.

As the first unit in the OpenSciEd program, during the course of this unit, students also develop the foundation for classroom norms for collaboration that will be important across the whole program.


Unit Examples

Additional Unit Information

Building Toward the Following Standards and Practices
Performance Expectations

This unit builds toward the following NGSS Performance Expectations (PEs): 


  • Develop and use a model to describe that waves are reflected, absorbed, or transmitted through various materials.


  • Gather and synthesize information that sensory receptors respond to stimuli by sending messages to the brain for immediate behavior or storage as memories.
Disciplinary Core Ideas

The unit expands students’ understanding of particle models and energy transfer, which include these Grade 6–8 DCI elements: 

PS4.B: Electromagnetic Radiation

  • When light shines on an object, it is reflected, absorbed, or transmitted through the object, depending on the object’s material and the frequency (color) of the light.
  • The path that light travels can be traced as straight lines, except at surfaces between different transparent materials (e.g., air and water, air and glass) where the light path bends.

To fully explain why a person on one side of the one-way mirror primarily “sees” one thing, students must account for how the eyes detect light inputs and transform them into electrical signals sent to the brain. Therefore this unit includes the following:

LS1.D: Information Processing

  • Each sense receptor responds to different inputs (electromagnetic, mechanical, chemical), transmitting them as signals that travel along nerve cells to the brain. The signals are then processed in the brain, resulting in immediate behaviors or memories.

*There is a strike through part of the DCI elements that are not developed in this unit. The placement of this OpenSciEd Unit 6.1 and associated units are shown in the OpenSciEd Scope and Sequence


Focal Science & Engineering Practices
  • Asking Questions & Defining Problems
  • Developing & Using Models
Focal Crosscutting Concepts
  • Systems & System Models
  • Structure & Function
Unit Information
What are prerequisite math concepts necessary for the unit?

In Lesson 3 students will collect light sensor data under very specific measurement conditions in which any deviation from the protocol could result in measurement error. Even given the detailed protocol students follow, the light sensor will not consistently report a single value, so students will need to determine a range that seems as accurate as possible given the measurement conditions. When they rank order the materials by transmissivity and reflectivity, they will use ranges that could overlap for some materials, and students may need to estimate the central tendency within the range of values to help them determine their rankings. This work is largely done as a whole group and can be more or less guided by you. However, the following math concept may be helpful:

  • CCSS.Math.Content.6.SP.A.2: Understand that a set of data collected to answer a statistical question has a distribution which can be described by its center, spread, and overall shape. Additionally, students collect these data using base tens (x10 lux).

The following math concept will be useful in explaining why they are selecting this setting on the light sensors.

  • CCSS.Math.Content.5.NBT.A.1: Recognize that in a multi-digit number, a digit in one place represents 10 times as much as it represents in the place to its right and 1/10 of what it represents in the place to its left.

Consult with your students’ math teacher(s) prior to Lesson 3 to coordinate your approach to the math concepts listed above with what your students will experience in their math classes.

What modifications will I need to make if this unit is taught out of sequence?

This is the first unit in the OpenSciEd materials and intended to be used at the start of 6th grade. Given this placement, several modifications would need to be made if teaching this unit later in the OpenSciEd curriculum. These modifications include the following:

  • The unit spends time introducing the students to a Driving Question Board. This would not be necessary if taught after other OpenSciEd units.
  • The unit helps the class develop and practice a shared set of classroom norms. If this unit is taught later in a school year, the norm-building process would need to happen in an earlier unit and could be streamlined here.
  • This unit focuses on reinforcing many grades 3-5 elements in all three dimensions. This reinforcement is intentional as preparation for students to begin building on those elements in the grades 6-8 space. If this unit is taught later in the OpenSciEd sequence, modification to these elements would need to happen so that this unit is less about reinforcing grades 3-5 and more about building elements in grades 6-8.
  • This unit is the first unit in an intentional sequence to build two Performance Expectations: MS-PS4-2 and MS-LS1-8. The DCIs associated with these Performance Expectations are fully covered across multiple units. The approach to these DCIs will need to change if this unit is taught after other units addressing the same, or closely related, DCIs.
Unit Acknowledgements
Unit Development Team
  • Lindsey Mohan, Unit Lead, BSCS Science Learning
  • Zoe Buck Bracey, Writer, BSCS Science Learning
  • Emily Harris, Writer, BSCS Science Learning
  • Audrey Mohan, Writer, BSCS Science Learning
  • Tracey Ramirez, Writer, The Charles A. Dana Center, The University of Texas at Austin
  • Abe Lo, Reviewer, PD design, BSCS Science Learning
  • Michael Novak, Conceptual design, Northwestern University
  • Misty Richmond, Pilot Teacher, James Ward Elementary School, Chicago Public Schools
  • Ty Scaletta, Pilot Teacher, Alcott College Prep Elementary School, Chicago Public Schools
  • Keetra Tipton, Pilot Teacher, Aptakisic Junior High School, Buffalo Grove, IL
  • Katie Van Horne, Assessment Specialist, Concolor Research
  • David Fortus, Unit Advisory Chair, Weizmann Institute of Science
  • Susan Gomez-Zwiep, Advisory Team, BSCS Science Learning
  • Dominique Poncelet, Advisory Team, Southeast Middle School, Oklahoma City Public Schools
Production Team

BSCS Science Learning

  • Maria Gonzales, Copyeditor, Independent Contractor
  • Kate Herman, Copyeditor, Independent Contractor
  • Stacey Luce, Copyeditor and Editorial Production Lead
  • Renee DeVaul, Project Coordinator and Copyeditor
  • Valerie Maltese, Marketing Specialist & Project Coordinator
  • Chris Moraine, Multimedia Graphic Designer
  • Kate Chambers, Multimedia Graphic Designer
Unit External Evaluation
NextGenScience’s Science Peer Review Panel

An integral component of OpenSciEd’s development process is external validation of alignment to the Next Generation Science Standards by NextGenScience’s Science Peer Review Panel using the EQuIP Rubric for Science. We are proud that this unit has earned the highest score available and has been awarded the NGSS Design Badge. You can find additional information about the EQuIP rubric and the peer review process at the nextgenscience.org website.