Before reading the article I knew that motion detectors used heat sensors to detect people. They also used echo-location to find differences in the rebounding echo. I learned that motion detectors need another sensor to receive the waves or echo that it is emitting. I also learned that motion detectors use electrons and the photo-electriceffect. I also found out that rattlesnakes have pits on the sides lf their head that can detect infrared light to locate their prey in the dark.

Clearly write about three things you knew and three things you learned. 4 stars. MW

In the video I found it interesting that crude oil is distilled in to different oils. I didn't know that different distilled oils are used for different fuels and gas. Large fractional stills are used to seperate all the oils at once. I found it interesting that big manufacturers use these and spereate all the oil, fuel, and gas they need at once. I learned that the still works by heating the bottom crude oil at the boiling point and as the oils become vapors they cool as they rise up the still. As they cool they condense in a certain area of the still and exit through the arm.


Good comments! You got it. 5 stars. MW

I read the article Trick Candles. Before reading I knew that trick candles reignite from sparks and that Canada banned trick candles in 1977. I also knew you must run candles under water to assure they are out. I learned that trick candles reignite because of magnesium powder that relights at 800 degrees fahrenheit and candles can cause fires by being thrown out, then reigniting in the trash. I also learned colored flame candles are not often available due to lack of research on the toxicity of their emissions.

Looks good. 5 stars. MW