Recently students at Morrison Labs completed the Rainbow Straw Challenge. In this density challenge students discover that liquids of diferent densities can be layered. To become "Straw Masters," students had to determine the correct order of four colored salt solutions to make a rainbow straw. Next they were challenged to do the same thing in a test tube. Finally, students could become "Rainbow Straw Grand Masters" if they successfully layered five colors in a straw.
2002 Gallery of Rainbow Straw Experiment Pictures
2000 Gallery of Experiment Pictures
Try out a cool online density experiment!
http://ippex.pppl.gov/interactive/matter/denslab.html
Find the dead sea on the map to below. The Dead Sea receives its water from the Jordan River to the north. Because there is no outlet for the water it sits there and evaporates leaving one of the highest concentrations of salt in any lake in the world.
"The Dead Sea, located in the Middle
East, between Jordan and Israel, contains some of the
saltiest water in the world. It's almost six times as salty
as the ocean. Because of the Dead Sea's high salinity, no
plants or animals live there. Since human bodies have a
lower density than the water of the Dead Sea, people can
float in it effortlessly. The extremely salty water holds
people up instead of letting them sink." The pictures below
show people floating in the Dead Sea. The picture below shows people floating
in the Dead Sea. This lake is one of the saltiest lakes in
the world. Regular ocean water has 35g of salt per liter
(1,000 ml). The Dead Sea has 345g per liter (1,000 ml).
Because of the high salt content and therefore high density,
people can float very high on the Dead Sea's surface.
Below is a satellite view of the Dead
Sea. It is 400 meters below sea level making it the lowest
point on the Earth's surface.
Try out a cool online density experiment!
http://www.explorescience.com/activities/Activity_page.cfm?ActivityID=29 Hypatia was an amazing women for her
time. She invented the hydrometer which can be used to
measure the density of liquids. She was one of the greatest
teachers and thinkers of her time. To learn more try the pages below: http://www.geocities.com/Athens/Delphi/1836/ http://www.mcs.drexel.edu/~crorres/Archimedes/contents.html Archimedes did several experiments that
laid the foundation for calculating the density of objects.
Fin out about how he solved the mystery of the golden crown.
Eureka I found it! http://www.cdc.gov/powerfulbones/
Below are some density cards that I use to help illustrate the rainbow straw lab. I print large versions of them and put an adhesive magnetic backing on them so they can go up on my magnetic whiteboard in the classroom. Each color can be arranged in order of density.
The Story of the Straw
Marvin Stone, a manufacturer of paper cigarette holders, created drinking straws in 1888, according to Steven Caney's "Invention Book." Stone, who had a factory in Washington, D.C., enjoyed visiting a tavern after work for his usual drink, a chilled mint julep.
Because mint juleps lose their flavor when warmed, people drank them through natural grass straws so they wouldn't have to touch the glass. Unfortunately, the natural straws - often cut from rye - tended to make the drink taste like grass.
Stone saw a connection between the process for making his cigarette holders and making a paper-wound, artifical drinking straw. Spurred on by the prospect of a better - tasting mint julep, he started winding long strips of paper around a pencil and fastening the loose end with a dab of glue. Soon other patrons wanted to try his paper tube straws for their mint juleps.
Reasoning that people would enjoy drinking lemonade through a straw, too, Stone designed an 8 1/2-inch paper straw with a diameter just wide enough to prevent a lemon seed from lodging in the tube. He used a paraffin - coated manila paper so the straw wouldn't become soggy when put into liquids.
Stone patented his straw, and by 1890 most of the employees at the Stone Cigarette Holder Factory were winding artificial straws. In 1906, eight years after Stone's death, the first machine - made drinking straws were manufactured with a steam - powered engine.
Richard A. Norris / Buffalo News
Buffalo Magazine / October 13, 1985
