About Carolyn L

Carolyn coordinates the Science on Stage outreach program at HMNS and will blog about science toys and experiments, logic puzzles, and whatever else seems interesting at the time.

Science Starts with density and distance

A rousing game of “Will it Float?” occasionally played on The Late Show with David Letterman was really just an impressively popular density guessing game. In our recently added Science Start Outreach Program, Discovering Density, we play a similar game, predicting and testing to see what happens when you toss things into a tank of water. The Science Start program is for grades K-2 and travels to schools, daycares, scout groups, and more to educate students with hands-on learning experiences. 


Sahil tests the hypothesis that a tiny metal car is denser than water and will sink.

The most fun results are the ones that surprise the young students, like a whiffle ball that will not sink even though it is full of holes, a Lego brick (you’ll have to test that one out for yourself), or liquids that can float on or sink through other liquids in a density column.


Carolyn points out to a class at Passmore Elementary that an object that is floating must be touching the surface of the water in a presentation of the new Discovering Density program.

Making the distinction that density isn’t just about weight or mass or size but instead the comparison between the two can be a tricky concept at first. Similarly, very small and very large numbers, distances, and time scales can be difficult to grasp, so to make it a little easier, you could try holding a planet like Jupiter or maybe Neptune, if you prefer, as we model the vast distances of our solar system and think about scale in Space: Going the Distance.


Carolyn points out the different types of liquids forming four distinct layers in the density column that she made during the presentation. The density column was given to the group’s teacher after the show so that students could watch it change over time.

Volunteers spread out with their planets to see the relative spaces between their orbits and explore what a model is, why it’s helpful, and what about the model isn’t quite as it is in real life. For our model to be to scale for both the sizes of the planets and for the distances between them is tricky—in a classroom-sized solar system, it’s going to be almost impossible to see most of the planets from most seats, and even the sun seems petite!


Carolyn holds up a three-foot board that models the planet Jupiter. If Jupiter was just three feet across, the Sun would have to have a diameter of 23 feet!

Book Science Start for your school or scout group today by contacting Greta Brannan at (713) 639-4758 or outreach@hmns.org. For more information on HMNS outreach programs, click here.

Please, Be Irrational! Pi Day is Tomorrow!

pi-dayTomorrow is Pi Day, a slightly silly recognition of the special number that is the ratio of a circle’s circumference to its diameter. But it’s not just any Pi Day, it is the Pi Day of the century! Because pi is 3.1415926……..etc., Pi Day is held on March 14 every year (get it? 3-14?), but Pi Day this year is special because it is 2015, so now we can have 3-14-15, which won’t happen again for a hundred years!


For extra bonus, give a cheer at 9:26 am (and 53 seconds!) to squeeze in a few more place values of joy. But you’ll have to make a cut-off somewhere because pi just keeps going, and going, and going without repeating patterns.


It has been calculated out to a trillion digits (thanks, computers!) but most of the time, there’s no reason you’d need more than a couple dozen at the very most. Happily, for everyday estimations 3.14 will get you there, or 3.14159 if you want be more accurate.


Want to remember pi more easily? Use the delightfully geeky trigonometric chant:

Cosine, secant, tangent, sine!
Three point one four one five nine!


Find yourself in pi’s digits: Use the birthday (or other date) finder from www.mypiday.com to see where your date shows up in the endless string – it’s pretty, too!


Want some gear to along with that pi? We’ve got your covered!


Join us for a Pi Day celebration at HMNS Sugar Land the morning of 3/14/15, or check out more fun with pi from www.piday.org

Happy Pi Day, Everyone!

Educator How-To: Crystals, Geometry and Chemistry

Math is beautiful and inescapable. Especially in nature, patterns and equations just keep showing up.  The path of an orbiting planet, the growth of a nautilus, arrangements of leaves on a stem, the efficient packing of a honeycomb; we can find rules and algorithms and make predictions from them.

Crystals, with their obediently repeating structure, are an elegant manifestation of the ‘rules.’  To be a crystal, your building blocks (atoms, molecules, or ions) must follow patterns over and over and over and over and over.  Atoms, being predictable, simply do what their chemical properties and the conditions (temperature, pressure, etc.) indicate.  So what exactly does it take to go from a mess of elements and compounds to this example from the Crystals of India exhibit at HMNS Sugar Land?

If you’ve ever tried making rock candy from sugar water or ornaments from borax solution, then you have some idea what it entails: something dissolved that is capable of making crystals has to slowly come out of solution – usually the longer you give it, the bigger it can grow and the slower it grows, the more perfect the crystals.

Freezing water into ice also gives you crystals; they just don’t stick around and let you handle them conveniently at room temperature. Water and solutions in water aren’t the only way to get crystals; molten rock cooling (slowly) can also give crystals, but that’s a little tricky for home experimentation.

So time is your friend for crystal growth, pressure is a factor, and it needs to be easier for atoms to attach to the forming crystal than to stay in solution.  Having a solution that is saturated or supersaturated so it can barely hold all of the dissolved material helps. It also helps to have places for the crystals to start forming; a tiny ‘seed’ crystal or sometimes even just a rough spot on a surface can provide the nucleation sites to kick off crystal growth. Are there other ways crystals and the things we consider ‘gems’ can form? Yes!

For those of us with shorter attention spans, a cool way so see the process is with crystallizing hand warmers – a pouch holds a saturated solution of sodium acetate. When you flex a metal disk inside the pouch, you kick off a chain of crystallization and end up with solid material (and released heat energy).  Because the process is so fast in the hand warmer, the individual crystals are very small and jumbled up (polycrystalline); oriented in all different directions, and as a mass they are opaque (light is refracting all over the place) and relatively dull rather than shiny and smooth as slower-forming large crystal faces can be.  The structure of most metals is also polycrystalline, and things like plastic and glass (even the kinds misleadingly labeled “crystal!”) are amorphous.

The external crystal shapes we see are related to the internal structure – there are a lot of different ways atoms can pack together.

Practically, there will always be some disruption in a crystal structure, no matter how perfect it may appear, which allows for some very cool effects – crystals “twinning,” impurities that alter the color; the reason ruby and sapphire (both corundum crystals) appear different.

Crystals aren’t always pretty! Sometimes we want to prevent crystallization to avoid things like kidney stones, but crystals are useful for all kinds of things; optical equipment and lasers, X-ray crystallography to figure out structures of proteins (and once upon a time, DNA), and silicon chips used in electronic devices. 

Whether you prefer your crystals practical or decorative, they are amazing!

Can’t get enough crystals? Check out the Crystals of India exhibit at HMNS Sugar Land (free for members!)



Glow on, get happy! Join HMNS this Friday for a fun-filled night of light at LaB 5555: GLOW

Whether they’re toys that shine in the night, black lights, glow sticks or fireflies, things that produce an eerie glow are fascinating. Give a kid a glow-in-the-dark toy or paper her ceiling in dimly shining plastic stars, and she will be occupied forever. She’ll find ever brighter lights to charge them up, ever darker places to view them for maximum glow effect, and generally love exploring how it all works.

You know this; you were that kid. So what’s the deal with the glow?

Enjoy a sip of the galaxy -- learn how to make this glow-in-the-dark cocktail at Neatorama

Learn how to make this amazing looking glow-in-the-dark cocktail over at Neatorama

It’s 10 p.m. Do you know where your electrons are?

While there are several “flavors” of things that glow, they all have something in common: Things glow because photons are emitted when “excited” (at a higher energy state) electrons drop back to a lower, more stable state. Aside from promising them a pony or a tour of CERN, there are several ways to get your electrons excited.

In chemical glow sticks, a chemical reaction excites the electrons. This process is called chemiluminescence. Glow sticks are an excellent way to experiment with reaction rates and temperature. If you want the reaction to last longer, follow a kid’s advice and put the glow stick in the freezer or in ice water so the reaction slows down; it’ll take longer to use up the chemicals in the glow stick. The trade-off is that because the production of photons is also slower, a cold glow stick is dimmer than a warm one.

Fluorescence is like light recycling. Fluorescent rocks, laundry detergent additives, paint, and even some animals can re-emit light after something shines on them. Usually we’re talking about things getting hit with ultraviolet or ‘black’ light and re-emitting within the visible spectrum. This makes sense because as you progress along the spectrum of electromagnetic radiation, visible light is a bit lower in energy than ultraviolet light — you can’t expose something to lower energy red light and get it to fluoresce in UV, for example. Fluorescent things certainly fluoresce in daylight, but not enough to outshine the ambient light, so they’re most noticeable under a black light in an otherwise dark space.

Phosphorescence is a lot like fluorescence but stretched out over time — a slow glow. So you can shine light (visible or UV) on a glow-in-the-dark star and it re-emits light, too, but over a lot more time, so the glow continues for minutes or hours before it completely dies out. If you have a glow-in-the-dark toy or T-shirt, try “charging it up” with lights of different colors or intensities and checking out the glow that results.

Nature glows

Fireflies produce and use their own chemicals, luciferin and luciferase, to dazzle and attract potential mates — and sometimes to lure prey. A surprising number of marine critters are bioluminescent, too, like dinoflagellates (plankton) that glow when disturbed, the angler fish, and some squid (perhaps they are blending in with starlight from above). Headlines occasionally announce a new genetically engineered “glowing” kitten, rabbit, plant, sheep, etc., but they are almost always talking about fluorescence instead of bioluminescence, so the light is only seen when the animal is placed under ultraviolet light. (One useful application of this is the ability to track a protein related to a certain disease by getting the introduced gene for Green Fluorescent Protein (GFP) to link to the gene for the protein of interest). Some animals like scorpions and jellyfish (the original source of GFP) fluoresce naturally.

Cheap thrills

Sugar and adhesives can exhibit triboluminescence, in which friction or fracturing produces the light. This one is great to try out at home; you just need Wint-O-Green Lifesavers®, transparent tape and a very dark room (a buddy or a room with a mirror is helpful for the Lifesavers portion). Dr. Sweeting (that’s her real name) has more detailed instructions and explanation, but the big idea is that a tiny, but visible, amount of light is emitted when you peel tape off the roll and when you bite into the candy, crushing sugar crystals against each other. The wintergreen oil even improves the effect by fluorescing!

Are there any other kinds of luminescence? Yes! Incandescence, piezoluminescence, radioluminescence, etc. But that’s enough fun for one post. Go try out triboluminescence!

Just can’t get enough? Make sure to come early for the educational portion of HMNS’ LaB 5555 this Friday for more GLOW fun, and learn all about the science of what gives things light. I’ll be there doing demos to light up your night. For tickets and more info, click here!