Indiana Science HS-PSII-9.2

ScienceGrades 9–12Physical Science

The Standard

Explain how electromagnetic waves interact with matter both as particles (i.e., photons) and as waves and be able to apply the most appropriate model to any particular scenario.

Indiana Academic Standards for Science (2023) · Particle and Wave Nature of Light

Teacher's field guide

What This Standard Means

What Students Need to Do: Students use wave behavior to explain patterns such as polarization and diffraction. They use photon energy to explain when matter absorbs light or releases electrons, then choose the model that fits the evidence.
What Mastery Looks Like: A student predicts how turning one of two polarizing sheets changes the light passing through them. They can explain why bright red light fails to eject electrons from a metal that responds to dim violet light.
Common Misconceptions: Students may think making red light brighter always gives it enough energy to eject electrons. They may also think wave and photon models cannot both be useful, or that a polarizer blocks light by color rather than orientation.
How to Assess It: Exit ticket: A metal releases electrons under dim violet light but not bright red light. Two crossed polarizers block a flashlight. For each observation, name the better model and explain why.

Lesson moves

Ways to Teach It

Shine a phone flashlight through two polarizing sheets; rotate one sheet and have students record brightness at four angles.
Ask why dim violet light can eject electrons from a metal when bright red light cannot; have students write a photon-based explanation.
Give pairs four cards: a diffraction grating, crossed polarizers, electrons leaving a metal, and atomic line spectra; sort by useful model and justify.
Give students a window film label stating “blocks 99% UV, passes 70% visible”; ask which photons pass through.

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