Slime Lords: There is nothing like slime to put a smile on a kid's face. We made traditional slimes like gak (made with Elmer's glue and borax) and oobleck (cornstarch and water), but also learned the difference between mucus and mucilage, why hagfish are the world's greatest slimers (https://www.youtube.com/watch?v=NYRr_MrjebA), and a new word: glycoprotein. We also tried our hand at molecular gastronomy and made some alginate worms and caviar:
Robots! The kids built some great projects this week.
Rockets! We learned about Newton's Three Laws of Motion, how they affect bodies at rest and in motion, and why it takes a gigantic rocket like the Saturn V to push a tiny space capsule into space. We put together some rockets from kits which used combustion engines for thrust and launched them Thursday to wild cheering! We also made some vinegar and baking soda rockets to take home.
Red spot in the picture is the rocket parachute
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Colonial Chemistry: Meanwhile, 300 years ago, back in 1714, we learned how people lived in a time without refrigerators and supermarkets. Colonial Americans used chemistry in their everyday lives without knowing it. They had no microscopes, so they couldn't see the magnificent little yeast cells growing in the bread dough, releasing bubbles of carbon dioxide gas, which get trapped in the long strands of gluten molecules formed when flour is mixed with water and kneaded.
Colonials didn't know why milk curdled when they added vinegar (the casein molecules in the milk denature and clump under acidic conditions), but they sure enjoyed the cheese that this process made.
Colonials made dyes out of natural products like beet juice, but didn't know why soaking cloth in an alum solution made the dye more colorfast (alum is a mordant, from the French word mordre: "to bite", a chemical that forms a complex with dye molecules which holds the dye to fibers).
Colonials made their own ink out of various substances. The ink the children brought home was made by a series of chemical reactions:
1. They boiled steel wool in vinegar for about 10 minutes. The acetic acid in the vinegar reacted with the iron atoms in the steel wool to make the yellow compound ferrous acetate.
2. Adding hydrogen peroxide to the yellow ferrous acetate solution turned it red immediately. Kids love this color changing magic! The oxygen from the hydrogen peroxide changed the yellow ferrous acetate into red ferric acetate.
3. Adding some strong tea to the ferric acetate introduced a new compound, tannic acid (it's what makes tea brown), turning the red solution dark black! The tannic acid reacted with the ferric acetate to produce ferric tannate, which precipitated out as tiny black "grit" suspended in the liquid: nice, black ink!
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Masters of the Mesozoic: The kids took a walk back in time to learn about prehistoric life, learning about the early cyanobacteria which made the oxygen in our atmosphere, to the weird creatures of the Cambrian Explosion...
...and finally to our most beloved ancient creatures, the dinosaurs! Our scientific knowledge of these ancient animals has changed and grown in recent years, such as why a plesiosaur could never lift or bend its neck like the Loch Ness monster is said to, how a (feathered!) T. rex stands with its body parallel to the ground, not rearing and dragging a lizard tail like in the old pictures...
NO!
YES!
...and how not all dinosaurs went extinct because scientists are now convinced that birds are the direct descendants of dinosaurs!
On the final day, they even got to meet one!
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