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This site has some great videos about light. This link will take you to one on reflection.
www.pbslearningmedia.org/resource/lsps07.sci.phys.energy.lightreflect/light-and-the-law-of-reflection/ First, we reviewed how black is the result of all color wavelengths being absorbed. Instead of reflecting a color back at us, it absorbs all of the colors like a sponge absorbs water. Then, we reviewed that white light is the result of all colors being reflected back at us- NO colors are absorbed.
To model this, we took color wheels and spun them so fast, the colors seemed to blend together until all we saw was white (or tan, depending on how fast or slow the wheel spun). After this activity, we learned that the three primary colors in light science are red, blue, and GREEN (not yellow, like in art!). We covered flashlights with red, blue, and green filters and then saw what colors they made when mixed. The kids were shocked to find out that when red and green light mix, it makes yellow! After that, we learned did an "exercise" to compare our heartbeats to each color's frequency. First, we reviewed that frequency is the number of total waves that pass a specific point each second. We learned how to find our pulse and then, after resting for a short time, took our pulse for 15 seconds to count our heartbeats. After that, we hypothesized what would happen to our heartbeats if we did jumping jacks for 30 seconds before taking our pulse. Students formulated hypotheses using the If...then... format we've discussed. They hypothesized that "If we do jumping jacks for 30 seconds, then the number of heartbeats per 15 seconds will increase (from our resting heartbeat count)." Students took their pulses after 30 seconds of jumping jacks and confirmed their hypothesis was correct- the number of heartbeats had increased. We then did activities for 1 minute and took our pulses (see below). They found that the more activity they did, the higher their pulses got. We compared our resting heartbeats to the color red's frequency. Our Resting heartbeats had the lowest frequency in 15 seconds, just like red's frequency is the lowest of the colors in ROY G BV. Resting = Red We compared our heartbeats after our lengthy exercises, when we had the most heartbeats (or a high frequency), to the color blue's frequency. We decided that when we were breathless, our heartbeats had a high frequency like blue. Breathless = Blue Then, we talked about how Violet has an even higher frequency than blue, so our hearts might be beating Violently in our chests- admittedly a bit of a stretch ;) See the image below to see the difference in frequencies. Red has less energy (just like we are using less energy when we are resting), and violet has more energy (like us when we are exercising!). Today we learned about how we see certain colors- objects do not actually have color "in" them, what we see is the surface of the object reflecting wavelengths of a color and absorbing the rest. For example, when light hits a banana, it reflects the wavelengths we see as yellow and the others (red, orange, green, blue, and violet wavelengths) are absorbed by the object. The wavelengths in the "visible spectrum" (those wavelengths we can see) can be remembered by the acronym ROY G BV-red, orange, yellow, green, blue, violet.
We also learned that what we see as the color white actually is the reflection of ALL of the colors' wavelengths in the visible spectrum and black is the result of the absorption all of the wavelengths. Makes sense that all of the light wavelengths are absorbed when we see black when you think of a "pitch black" room- a room with no light reflecting colors at us. After watching a Magic School Bus on how we see color, we did an investigation to discover that black absorbs all of the colors. We did this by "freeing" the colors and separating them from a line of black drawn with a marker. The kids were given a strip of a coffee filter with a black line drawn on it about an inch from the bottom of the filter. I used a scented black marker but any non-permanent black marker will work. We then held the end of the coffee filter in the water (without submerging the black line) and let the filter absorb the water up the filter. As it did this, the kids saw all of the colors separate from the black line! |