Under Construction: Building Up STEAM Bulletin Board in September

Since this was taken, there is content in every section except "Internet Links" and we are working on that. More to come!

MATH: A problem to solve

Answers to Math problems will appear in a newsletter to families.

MATH: A problem to solve

Answers to Math problems will appear in a newsletter to families.

THIS MONTH IN SCIENCE: Leaves

An October update to our STEAM Bulletin Board!

COOL SCIENTISTS: Dr. Neil deGrasse Tyson

Dr. Tyson was born in 1958. He was raised in New York City and became interested in astronomy when he was 9 years old during a visit to the Hayden Planetarium at the American Museum of Natural History.

He attended public schools, including the Bronx High School of Science, and then went on to graduate from Harvard University with a bachelor’s degree in physics, University of Texas at Austin with a master’s degree in astronomy, and  Columbia University with both master’s and doctorate degrees in astrophysics.

Dr. Tyson’s research as an astrophysicist and cosmologist includes the formation and evolution of stars. He is now the Director of the Hayden Planetarium in New York City that once inspired him! He also has become a very successful science communicator, exciting the public about science through his work at the planetarium and through television, books, and public speaking.

Books:

“The Sky Is Not The Limit: Adventures of a urban astrophysicist” (2000)

“Origins: Fourteen billion years of cosmic evolution” (2004)

“Death by Black Hole” (2007)

“The Pluto Files: The rise and fall of America’s favorite planet”(2009)

“Space Chronicles” (2012)

TV series:

Nova: ScienceNow

StarTalk

Cosmos: A spacetime odyssey

D.I.Y. (Do-It-Yourself): Ice cream chemistry

S A F E T Y  P R E C A U T I O N S

• Make sure your work area is not cluttered, that you have enough space for your activity, and that you have all of the things that you need handy before you start.
• Wear a cotton apron or smock if there is anything that might stain or damage your clothes.
• Use gloves or other hand protection when working with very hot or cold items.
• Tie back long hair.
• Avoid using glass containers.
• Always wash your hands after you’re done doing science.

You will need:

• Quart-sized ziplock freezer bag
• Gallon-sized ziplock freezer bag
• Half-and-half (1/2 cup per serving)
• Sugar (1 Tablespoon per serving)
• Vanilla (1/4 teaspoon per serving)
•  Crushed ice (3 cups per batch)
•  Rock salt (1/3 cup per batch)

Directions:

1. Put half-and-half, sugar, and vanilla in the quart-sized ziplock bag and seal well (make sure to test seal). 
2.  Put ice and rock salt in the gallon-sized bag and then put your smaller ice cream bag inside before sealing the large bag. So now you have the smaller bag of ice cream ingredients inside the larger bag of ice and salt.
3. Shake and squeeze larger bag until ice cream thickens (careful not to pop inside bag). It takes about 15 minutes of constant movement. You will probably want to wear winter gloves or mittens for this since the bag will get colder than the original ice!
   

Chemistry involved in making ice cream:

Everything around us is made up of molecules—these are itsy bitsy building blocks. Heat and cold affect molecules. This kitchen science activity explores what happens when the molecules of protein and sugar and fat and water get cold and…well, here are some science facts about making ice cream from a chemist who is also a parent at PHA.

The Mixture:

When you mix the sugar into the half and half, you are making a syrup. In Chemistry terms, you are making a concentrated solution of molecules (itsy bitsy individual pieces of milk protein or sugars) dissolved in water (most of milk is water).  You are also making a homogenous suspension of the fat particles in the cream distributed throughout your sugar solution.

The Freezing:

To make this tasty syrup into ice cream, you need to freeze it. However, concentrated solutions don’t freeze at the same temperature as pure water freezes into ice.  Because of interactions between the water molecules and the sugars and other things dissolved in your solution (the solutes), the freezing temperature of the solution is lower than that of pure water.

So, how do you get the solution to freeze if it needs to be colder than the temperature that freezes water? That’s where the rock salt comes in! The salt has the same behavior with water that your concentrated solution does—it lowers the freezing temperature of water because of attractive chemical forces between the salt and the water as the ice melts. This lets us get down to a colder temperature than where water normally freezes to ice—colder than 32 degrees Fahrenheit.

Why the ice cream solution needs to be colder than water to freeze:

If you freeze a solution, all of the individual water molecules need to separate from the solutes they are close to (all the sugar, protein, or salt molecules) to form ice. Solid ice is a crystal of only water molecules touching each other in a very specific, ordered way. Everything else needs to be squeezed out from in between the water molecules for ice to form. Because it takes energy to break all of the water-solute interactions, you need a greater driving-force for freezing the water (a lower temperature).