1-PS4-2: Seeing Needs Light
Also called NGSS 1-PS4-2 · Topic: Waves: Light and Sound · Physical Science
The Official Wording
Make observations to construct an evidence-based account that objects in darkness can be seen only when illuminated.
Clarification statement: Examples of observations could include those made in a completely dark room, a pinhole box, and a video of a cave explorer with a flashlight. Illumination could be from an external light source or by an object giving off its own light.
NGSS Lead States, 2013 · Read it on nextgenscience.org · checked October 15, 2026
What 1-PS4-2 Means in Plain English
First graders find out that eyes need light to see. In a very dark space they cannot see a picture right in front of them, but once a flashlight shines on it, or a glow stick lights the space, they can. What they saw becomes their evidence.
Light can come from a lamp shining on an object or from an object that glows by itself, like a glow stick or a firefly. How light bounces into the eye is saved for 4-PS4-2. Next, children test what light does when it meets different materials (1-PS4-3).
1-PS4-2 I Can Statements
- I can explain why I cannot see things in the dark.
- I can tell that light helps me see objects.
- I can name things that give off their own light.
1-PS4-2 Worked Example
A blanket fort test a class can run in a darkened room with a few picture cards.
Can we see a picture in total darkness, or do we need light?
Set It Up: A thick blanket draped over a table in a room with the lights off and blinds down, picture cards, a small flashlight and a glow stick.
- Two children crawl under the blanket, tuck the edges down, and hold up a picture card.Card cannot be seen
- Wait a whole minute for eyes to get used to the dark, then look again.Still too dark to tell what it shows
- Switch on the flashlight and point it at the card.Picture is clear
- Turn the flashlight off and snap the glow stick.Glow stick is easy to see, card is faint
- Back at their seats, children draw what they saw each time and where the light came from.Drawings: no light, flashlight, glow stick
The children saw the card only when light reached it, and they saw the glow stick because it made its own light.
Why it works: We see an object when light from it reaches our eyes, either light bouncing off it from a source or light it gives off itself.
Common Mistakes with 1-PS4-2
Thinking eyes give off light
“If I open my eyes really wide, I can see in the dark.”
Try this: Try it under the blanket with eyes wide open. Without light coming in, nothing shows, so eyes catch light rather than make it.
A dark room that is not really dark
A classroom with the lights off but sun peeking through the blinds
Try this: Light sneaking past the blinds lets you see a little. Cover every gap, or use a blanket fort, to test true darkness.
Thinking shiny things glow
“The mirror lights up by itself.”
Try this: A mirror or foil only shines back light that hits it. In full darkness it vanishes, while a glow stick still shines.
Where 1-PS4-2 Fits
Practice 1-PS4-2
Quick Check
- Your bedroom is totally dark. Why can't you see your teddy bear?
- Name something that gives off its own light.
- Why can you see the moon at night?