Ice cream science: Make a cool treat to beat the summer heat

It’s getting to that time of year when it’s so hot and yucky outside that everything cold is better.

It’s also a time for telling kids about how, when you were their age, if you wanted ice cream you had to turn a crank until your arms fell off (presumably while walking uphill to school both ways and fighting off bears…).

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Here in the Houston Museum of Natural Science education department, we have tried making ice cream in a variety of ways to see what is easiest for kids, and not all ways are equal. (Pro tip: Those special ice cream-making balls they sell for kids freeze shut, and then kids are sad. Not recommended.) Our favorite way, at the end of this post, is fairly cheap and easy and fun for kids, but before we get to the instructions, let’s talk about some science.

To make ice cream, you will of course need ice. The ice is simply to lower the temperature of the cream to the freezing point, but if you just used ice alone and let it sit, you’d end up with a solid block of cream – more like an ice cube – and it would take longer to freeze. What makes ice cream special is salt and stirring.

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Water freezes at 32° F, but sprinkling salt on the ice lowers the freezing/melting point of water. How, you say? In order for liquid water to freeze to solid ice, all of the water molecules have to slow down enough to connect to each other and form solid crystals. When this happens, the water loses kinetic energy due to the decrease in movement of those molecules. Because temperature is a measurement of kinetic energy, this results in a lower temperature.

The presence of salt interferes with this process. The water molecules can’t attract each other as easily because they are also attracted to the sodium and chloride ions from the salt. Mixing the salt, ice, and water together results in a temperature below the freezing point of water, which helps the cream freeze faster. The shaking or stirring helps cool the cream evenly and efficiently. In ice cream, this lower freezing point turns the fats into solids, but the water content to be almost frozen.

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What about the milk, then? It is much easier to make ice cream with creamer, heavy whipping cream, or half-and-half than to use skim milk because of the higher fat content in cream. You can make ice cream with skim milk, but it is really, really, really hard to do by hand, AND you have already committed to making ice cream, so I feel like you have acknowledged the inherent risk of fat consumption that comes with making a frozen confectionery delight. Just use the full-fat stuff, and let’s all move on.

What does the fat do, anyway? Primarily the higher fat content allows for a richer, creamier texture and a more delicious flavor in your finished product. The reason for this is that when you are cooling and mixing the cream, you are also introducing air molecules to the liquid. The bits of fat in the cream add a little structure to the ice cream and trap these air molecules in the solution as it forms. This, plus the lower freezing temperature, enables you to be able to scoop the ice cream fairly easily because it allows for there to be a bit of unfrozen water in the ice cream, which stops the ice cream from becoming a solid block of ice.

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If you have ever had ice cream that has grown ice crystals and gotten a bit of freezer burn, those ice crystals appeared because the unfrozen water in the ice cream had a chance to migrate a little bit when the ice cream was warmed slightly on the ride home or when it was left on a counter a little too long and then frozen again. There are things called stabilizers added to your ice cream to prevent this from happening. Most ice creams today have one of five stabilizers added to them: carob bean gum* (a type of bean from Africa), carrageenan (a type of algae), guar gum (a type of legume from India), sodium alginate (made from seaweed) or carboxymethyl cellulose (sounds scary but it’s plant-based). Often, if you read the label, you will see more than one of these in your ice cream to keep it smooth and delicious.

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* Carob beans, or locust beans, are cool. They are from exotic African trees and each bean is so similar that at one point they were used as a unit of measurement for gold and silver. We still use this measurement today, but the name has changed over time to Karat.

So now that you have had a little lecture about the science of ice cream, let’s get to the delicious lab work.

 

Activity: ICE CREAM!!!!

Materials:

Individual serving containers of coffee creamer

Ice

Small waterproof container or quality sealable plastic sack big enough for about two or three cups of chipped ice

Salt, any variety

A dish towel to insulate your hands

Optional: Inexhaustible energy of small child-based labor

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Procedure:

  1. Find some liquid coffee creamers in individual pots.
  2. Put ice in your water proof container, filling it about a third of the way. Smaller chunks of ice work better because there is more surface area, but any ice will do.
  3. Layer your salt on your ice. Several solid sprinkles will do, but if you are nervous about the quantity, add some extra just in case. It won’t hurt anything.
  4. Put your sealed creamer cup(s) in your container and then put more ice in, filling it about 2/3 of the way.
  5. Layer on more salt.
  6. Finish filling the container with ice.
  7. Start shaking your container. Make sure it is well sealed and that you have a firm grip on it. No one wants to be injured in an ice cream-related accident. There is no way to spin that so it sounds cool. Also, this is an excellent job for kids to help with. Put on a nice, long song or two and let them wiggle till they drop. About ten minutes will do it, but you will know when you are getting close because a frost will form on the outside of your container. If you don’t feel frost forming after a couple of minutes, add more salt. To speed this process up, start with creamer pods that have been stored in the fridge. This way, your creamer will start at about 50° F, and you won’t have to work so hard.
  8. After about 10 minutes of shake, shake, shaking your ice cream, dig your creamer cup out of the ice and wipe it off.
  9. Ta dah! You are done. Unless you want to make this tablespoon of delicious homemade ice cream into a sundae and add chocolate and banana or some jelly for more flavor.

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Note: If you are thinking to yourself, “That seems like a lot of work for a tablespoon of ice cream,” well… it is. But it’s also science. So there.

If you get the liquid creamer that comes in a larger container at the grocery store, you can increase the volume of your creamer and make MORE ice cream. If you choose to do this, you will need to find a small waterproof (and I would suggest plastic) container to pour the creamer into and then a slightly larger waterproof container for all the ice and the salt. It’s the same procedure, just with a larger amount of the ingredients!

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The Things I Made at Summer Camp

Xplorations Summer Camp has been an integral part of summer at the Houston Museum of Natural Science for decades, and it was a large part of my childhood too. Over the years, I took all sorts of camps covering subjects like butterflies, cultures in the Americas and roller coasters. I made so many things at camp that I could probably have an entire exhibit called “Things I Made at Camp!” However, like fossils and artifacts, not all of my camp collection has survived to the present day. I wanted to see which items survived the decade since their creation, so I went on an excavation in my childhood home to uncover some of the lost artifacts.

First stop, my childhood bedroom. Among the stuffed animals and children’s books, I find many remnants of my childhood. Papers from school, photos from birthday parties, but no sign of Xplorations Summer Camp. Then, in the distance, I spot a woven basket. The woven basket (ca. June 1997) was made in a camp covering the cultures in the Americas. While I toiled weaving the reeds in and out, we talked about how many cultures wove baskets to hold food and water. To be honest, this woven basket is not my best work. It could certainly not hold water, and there aren’t many foods that can fit inside. In fact, it has a very distinct lean. It looks like it shares some characteristics with a cornucopia.

20150530_162901Onwards! As I search through my desk, I find the remnants of my emergency kit (ca. 2001) made in Survivor Camp. The original kit was encased in a convenient fanny pack, but the fanny pack has since vanished. All that remains is an emergency blanket, glow stick, and some matches in a waterproof container. If need be, I can survive a cold, dark evening with only these three supplies and the skills I remember from camp. I do miss the fanny pack though. Now that was survival and convenience all in one.

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My search continues. I have combed through all of the things in my room, and in a last-ditch effort I turn my search to the closet. Attached to my navy JanSport backpack, I find a handmade bead animal (ca. 1999). I was an after-camp kid, so I got the chance to make some fun crafts like bead animals after we finished the normal camp day. This particular bead animal was very special because of the rare sparkle blue pony beads that were used for the eyes. In the after camp world, those beads were a prized commodity.

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Eventually, I realize that my search has run cold. There are no more camp crafts to be found. I remember how some of them have been lost. In a medieval camp, I made potpourri and planned to give it to my dad for Father’s Day. Unfortunately, I was a clumsy kid and dropped the glass jar of potpourri on the floor. It did not make it home from camp. I’m sure a number of other camp crafts were dropped in puddles, broken in backpacks, or simply left behind. For all of those lost camp crafts, there are a number of memories that stay with me. As summer camp 2015 commences, I like to think that new campers will make some memorable camp crafts too! Let’s hope that they all make it home!

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Editor’s note: HMNS is in its first week of Xplorations Summer Camp right now! Registration is open to children ages 6 to 12. Camp runs Monday through Friday from 10 a.m. to 3 p.m., and care is available before camp from 8 to 10 a.m. and after camp from 3 to 5:30 p.m. for an additional fee. Live near Sugar Land? Register for camp at our sister location, HMNS Sugar Land. Be a part of the tradition at HMNS Xplorations Summer Camp, and like Kelsey, let your child learn and build lasting memories at the museum.

Take It: HMNS shopping trips rival Liam Neeson’s shakedown

May is upon us, which means it is time for stocking up on mosquito repellent and sunscreen, flip flops and floppy hats, bathing suits and beach towels. For the education staff at the Houston Museum of Natural Science, it also meanstake it heavy lifting and preparing for the emotional gauntlet that is summer camp shopping. Julia does the bulk of the mass ordering, but there are some things we just have to go to a brick-and-mortar store to get. So off to the store we go! Usually three or four hours at a time.

Generally, when we get to the store we take it. We take it all. Just like Liam Neeson.

The most common quantity on a shopping list is “all of them.”shopping list

We are like a plague of locusts, actively demolishing orderly displays of stock, leaving only a husk behind. If you are the unfortunate person who comes behind us looking for just one single solitary bottle of green food coloring, I’m sorry. Because I took them all.

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Inventory before HMNS hits…

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…and after.

On this particular trip, we start in what we affectionately refer to as, “bathroom.”  This is all the stuff that you might keep in your medicine cabinet, make-up drawer or shower. It’s a fairly small section in our shopping adventures, but it almost fills a basket by itself. “Bathroom” is a weird mixture of heavy items and small items. They have a tendency to sneak out through the holes in the bottom of the basket if you aren’t keeping an eye on them.

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We need all the cotton balls!

That white box? It’s an entire container of cotton balls. Why? Because we need them all.

After about an hour, in which Julia and I cover “bathroom,” “appliances,” and “party” (and I’d like to point out that it’s always a party in our department), we take a short break and check the list before heading to “craft” and “office.” There is no lunch break until the basket is full. Once we reach the point of having to carefully place items so they won’t fall out of the basket, trailing behind us like breadcrumbs, we decide it’s time to stop for lunch.

With special permission from Josh, the assistant manager, and promises from the clerks that no one will try to put our treasures away, we drop our first basket near the front and head for a quick “strategy meeting” (which is actually code for lunch), which allows Julia to double-check the list. Again. For the fourth time.

“I don’t know who you are.  I don’t know what you want. But if you are looking for Raisinets, I can tell you they don’t have any.”

Our summer camp uniform shirts are navy blue. This also happens to be the uniform shirt color for employees at one of our frequented summer camp shopping spots. This coincidence combined with the fact that our shopping basket is always filled with nonsense, and plenty of it, ensures that we will be confused with store employees at least once during any excursion. I have discovered that it is often easier for everyone if I can just tell the confused shopper where the item they are looking for is located. Due to the fact that we often need so very many weird things of specific shapes and sizes, I can almost always tell them if the store has it in stock and where to find it.

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When customers come up to me asking where they can find an item, I just tell them; I know where almost all of it is, anyway.

On this trip, we are asked twice to lend a helping hand. The first time, it’s a guy looking for reading glasses (usually across from the pharmacy window), and the second is a corporate stocker looking for her product placement (Swedish Fish and Sour Patch Kids – on the bottom shelf next to gum). We have been asked to locate anything and everything including, but not limited to, powdered sugar, colored ping pong balls, decorative masking tape, Abuelita chocolate, and picture-hanging supplies. (In this particular instance I recommend 3M Velcro strips, at the very end of the hardware aisle.)

My favorite case of mistaken identity happens while shopping with Sahil. He and I have spent many a summer’s day at the store shopping for 12-inch yellow balloons (with birthday party supplies) and Cheez Whiz (usually in the cold cheese section, which is weird because it doesn’t actually need to be refrigerated). Usually when shopping, we make a list by section – garage, craft, clothing, etc. – and then divide and conquer with one of us on aisle 10 and the other on aisle 11. Because Sahil is so very nice and polite, I have come around the corner more than once, turning slowly because my basket is so full, and see him helping a customer reach an item on the top shelf or discussing the merits of the three coolers in front of them.

On one particular occasion, we’re short on time, so Sahil‘s concentrating on the list in front of him, determining what we have left to find, when a customer comes up and asks him for the location of the honey, which stumps him. Honey isn’t something we’ve purchased before, so Sahil politely tells the customer that he doesn’t actually know where the honey is located. He apologizes and goes back to his list. The customer insists he help her, but he again tells her he doesn’t know where the honey is. He suggests it might be in the breakfast aisle, maybe with syrup, and again goes back to his list. The customer, feeling she’s been ignored, reports him to the store manager who then comes to chew Sahil out, the “unhelpful store employee.”

Oh, summer camp

“But what I do have is a very particular set of skills… Skills I have acquired over a very long career. Skills that make me a nightmare to people like you.”

dr mariotetrisWhen I was a child, my mom and dad purchased Nintendo Game Boys for my brother and I from a neighbor at a garage sale. I had two games I played regularly, Dr. Mario and Tetris. I was super good at both. We weren’t allowed to play our Game Boys a lot, but they were encouraged on road trips. I would play one of those two games for miles and miles, laying on the floorboard in the back of the sedan so my older brother could have the bench seat. Despite what my mom said, playing these games did not rot my brains out, though I do remember on more than one occasion, at the end of a long day of driving, dreaming of dropping pills and “tetrominoes.”

What seemed a pointless game for children has turned into a useful and particular skill as an adult.

I don’t love shopping. Never have. This combined with my Type A personality traits and the fact that shopping carts can only hold so much means that I have turned camp shopping into a game of sorts: Tetris – Museum Edition.

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Tetris: Museum Edition

When filling a cart, one should start with heavy and square items on the bottom, filling the gaps as the occasion arises. Hydrogen peroxide, for example, leaves just enough of a gap in the basket that you can tuck in your petroleum jelly to fill the space. When you have established a base layer, it’s time to start building side walls. These are the ramparts, allowing you to generate volume in the basket without an avalanche of Q-tips. Finally, top off your basket with bags of things to cement all the layers together. Generally, heavy bags work best, such as bags of candy, but use what you can. Once your basket can’t safely hold another item, it’s time to head to the check-out.

I’d just like to apologize to any check-out clerk that has ever helped me during summer camp shopping. They see us coming, with our two or three carts packed to the rafters, and the audible sigh can be heard three lanes over. We try not to be too irritating, but we know we are. The standard speech to the clerk goes something like this, “Hello (insert name here). We are making a tax-exempt purchase today. Whenever possible, we will put like items together for ease of counting. My colleague has gone to get an empty basket to help you out.”

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Car Tetris…

Inevitably when we check out, we end up with way more output than we had input due to my mad Tetris skills. On this particular trip, we have a one-to-two ratio of pre-check out baskets to post-checkout baskets, which I kind of consider a failure on my part. I think I could’ve done better. In my defense, this is just the first shopping trip of the season, and I haven’t stretched.

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…showing my particular set of skills.

Next comes car Tetris, where you take all of your goodies out to your vehicle of choice and build a mountain of things. As with the cart, you must start with the square and heavy items, then slowly build up to the items that can be crushed or smashed. On more than one occasion, I set my heights a little too high and have to pack stuff around my shopping companion. Today, the four baskets of treasure fit quite nicely into Julia’s back seat.  According to Julia’s Instagram, #wehadmoreroom.

The final stretch of any shopping trip is reverse Tetris, where the supply vehicle is met at the loading dock by all the worker bees, and we unload and sort the treasure. Depending on the trip, this could go a number of ways. We could sort by camp requests, by storage area, by weight, by refrigeration needs, and so on. Today’s trip?  We sort by storage location because, starting next week, we have INTERNS coming and we don’t want to deprive them of the opportunity to figure out where all this stuff goes!

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Reverse Tetris begins…

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…and game over. Now time to let the interns sort it out.

“If you have a case of glow-in-the-dark paint in the back, that’ll be the end of it. I will not look for you. I will not pursue you. But if you don’t, I will look for you. I will find you and I will bother you repeatedly.”

One of the trickier parts of camp shopping is when we need it, we need it now. If the store is out of stock, you go to another store. If that store doesn’t have it, you try at another place. On the hard-to-find items, we try to buy ahead or find a place we can order them, but that doesn’t always work, particularly if we are looking for a specific item for a specific purpose. Occasionally, even when there is a source for an item, we will run short and it becomes an emergency thereby causing us to hoard said item for years. I remember with dismay the Button Magnet Shortage of 2010 and the Silver Tinsel Crisis of 2008. Those were dark times… Dark times indeed.

Because there is a limited amount of time and a limited number of places, we have learned to be persistent. We ask questions. We know you have it in stock in the back… Please go look… And the poor clerk that runs into our brand of crazy, usually doesn’t understand our request.

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HMNS camp shopping isn’t for the faint of heart.

“How many do you want?”

All of them.

“But there’s like 50.”

Yes. All of them.

This style of shopping takes a minute to get used to and isn’t for the faint of heart or weak of muscle. And, once the summer has ended, you have to transition back to your normal life. Sahil, former shopping partner and current Outreach presenter, has fallen victim to this trap more than once. While at the store with his mom shopping for a big family dinner, he was sent off to get enough refried beans to feed 12 people. He returned with 12 cans.  His mother was not amused.

Our persistence usually pays off and, at the end of the day, we return victorious with the last carnivorous plant in town (or whatever the item might be).

Girl Scouts earn badges for science at HMNS

by James Talmage, Scout Programs

After more than a year of hard work, Girl Scouts Heidi Tamm, Zoe Kass, Meredith Lytle and her sister Angela Lytle completed the entire Scouts@HMNS Careers in Science instructional series, earning each scout a total of seven badges.

Careers in Science is the Scouts@HMNS series of classes for Girl Scouts that aims to introduce girls to different scientific fields, lets them meet women working in those fields, and shows them what it’s like to work at the museum. There are seven different classes: Archeology, Astronomy, Biology, Chemistry, Fossil Dig, Geology, and Paleontology. As the Fossil Dig class finished up March 7, those four girls added their seventh and final Careers in Science patch to their vests.

Girl Scouts accept badges for completing the Careers in Science series of classes at HMNS. Pictured from left to right are Angela Lyle, Meredith Lyle, James Talmage, Heidi Tamm, and Zoe Kass.

Girl Scouts accept badges for completing the Careers in Science series of classes at HMNS. Pictured from left to right are Angela Lytle, Meredith Lytle, James Talmage, Heidi Tamm, and Zoe Kass.

Heidi Tamm and Zoe Kass have been taking the classes together since the summer of 2013.

“They were really into earning all the patches and completing the whole series of classes.” said Julia Tamm, Heidi’s mother.

Heidi, whose favorite class was Archeology, said, “I liked science before the classes, but now I understand about the careers and what people actually do.”

Zoe kept taking the classes because of the fun activities and being able to see the museum in more detail. Her favorite class was Paleontology, which focuses on the Museum’s Morian Hall of Paleontology. 

Meredith and Angela, Girl Scout Cadette and Senior, respectively, have also taken all the classes together. Angela explained that she learned “there are lots of careers in science available and there are lots of women that work in science, especially at the Museum.”

Meredith encouraged other girls to try out the classes, even if they aren’t interested in science.

“You may decide you like it, or you’ll just learn something new,” she said.

The sisters agree that the Girl Scouts organization is moving more toward STEM (Science, Technology, Engineering, and Math) careers, and that it’s not a boy thing to go into science. Anyone can do it, especially Girl Scouts.

For more information on the Careers in Science series, visit http://www.hmns.org/girlscouts/ and start collecting your patches today!