Night Baking in the Marchetti Kitchen
1Leilani Marchetti bakes for her school's fall bake sale every year. This year her family put color-changing LED strips under the kitchen cabinets. One night, with the strips set to blue, she noticed that the strawberries on her cutting board looked almost black. A wooden spoon standing in a glass measuring cup of water also looked odd: it seemed broken at the water's surface, even though it was straight when she pulled it out.
2Her science teacher had explained that white light is a mix of many colors, and each color is light with a different wavelength. When light reaches an object, the object can reflect it, absorb it or transmit it, which means letting it pass through. What we see is the light that reaches our eyes. Light travels in straight lines, but its path bends where it passes from one clear material into another, such as from water into air.
3Leilani planned a test. She turned off every other light in the kitchen and set the LED strips to white, then red, then green, then blue, keeping the brightness the same. She placed each object on the same spot on the counter, 30 cm below the strips, and wrote down how it looked in each color. Her dad checked her notes by looking at the objects with her.
4Next she tested sound. While her mom whipped cream with the stand mixer on its highest speed, Leilani stood in the hallway 3 m from the mixer and measured the sound level with a sound-meter app. She measured with the kitchen door open, with the wooden door closed, and with a heavy blanket hung over the closed door. She also measured the hallway with the mixer turned off. A higher decibel (dB) number means a louder sound, and a drop of about 10 dB makes a sound seem about half as loud.
5Last, her brother Mateus tapped the far end of the stone countertop lightly with a spoon. Leilani listened from 2 m away, first with her ear pressed against the countertop and then with her head lifted into the air. The taps sounded much louder with her ear on the stone.