Pinhole Camera
Pinhole Camera is a simple box with a tiny hole that lets light in to make an image on the back wall.
A shoebox with a tiny pinhole in one end works the same way. Light from a bright scene outside passes through the hole. It lands on the inside back wall as an image. The image is upside down because light travels in straight lines and crosses at the hole.
Explaining pinhole camera by grade level
Light goes in a straight line through a tiny hole in a box. The hole is so small that it sorts the light. What is on top shows up on the bottom, so the image is flipped. You can use this to see a picture of the sun on paper.
Projects that explore pinhole camera
A tiny hole forces light to travel in straight lines from an object to form an image on the back wall — which is exactly how this sun-measuring instrument works. You tape aluminum foil with a pinhole to one cardboard box, then slide both boxes onto a meter stick and aim the pinhole at the sun. A bright image appears on the card inside the far box, created by sunlight passing through that single small opening.
A pinhole camera needs a box with one tiny hole and a back wall to catch the image. You build one from a cereal box with waxed paper taped inside as a screen. A thumbtack poke in the bottom lets light in through that single opening. You seal all edges so no stray light leaks in, and the scene appears on the waxed paper.
A tiny hole lets light pass through in straight lines, projecting an image onto the opposite surface. When you poke a small hole in a shoebox and aim it at the sun, the sun's disk appears on the inside of the box. Light travels through that single opening to create the projected image.