About Nicole

Nicole has worked for HMNS in some capacity since 1996, whether part-time, full-time or as a volunteer. She taught for seven years in public school, including four years in Fort Bend and a short stint overseas. While she never taught science, she was always the teacher called when someone needed to remove a swarm of bees, catch a snake in the playground, or get the bat off the ceiling of the cafeteria.

Holiday How-to: Chocolate Leaves

My mom was a chemistry and home-ec teacher, so I grew up in a home where ingredients were carefully measured and food items were attractively arranged. While I got to help out in the kitchen as much as I wanted, I always liked being in the kitchen around the holidays. There were always new tricks or special touches added to dishes and along with these came short science lessons on why we were doing things that particular way.

One of my favorite things to help with in the kitchen were chocolate leaves. When done correctly, these are perfect little molds of the living leaf, just like the perfect molds and casts in the Morian Hall of Paleontology.

A chocolate leaf is made by smearing melted chocolate onto a leaf and putting it into the fridge to harden. Sounds easy, right? It is pretty easy. Read on!


Activity: Chocolate Leaves


Leaves (*See note in step 1.)

Chocolate candy melts

Parchment or wax paper

A cookie sheet or plate for your leaves to rest on as they cool


1. Pick your leaves. I like to use slightly waxy leaves so you don’t have to worry about fuzzy bits in your chocolate. NOTE: Learn about the plant you are picking leaves from before you decide to use them. Many household plants are decorative but poisonous.  Oleander is a great example of a plant that is pretty but poisonous. If you hate botany or don’t know about the Internet, getting pre-packaged basil or mint from the grocery store is a safe way to go. These leaves will be a little less firm, so you will need to be more careful with them.

2. Don’t pick leaves from poisonous plants. Seriously.

3. Wash your leaves with soap and water, rinse them thoroughly and then dry them completely. The chocolate won’t stick to wet leaves, so don’t rush this step. You will only be frustrated.

4. Put wax or parchment paper on a cookie sheet or plate. You want this to be something that will fit in the fridge with no problems.

5. Get out your candy melts. The melts come in a hundred colors. We are using chocolate colored ones in this tutorial. There will be instructions on the package on how to melt the specific brand of melts you purchased. In general, you will put the melts in a microwave safe bowl and microwave them a few seconds at a time stirring as you go. Don’t overheat the melts. They get gross and there is no coming back from that.

6. When you have everything melted and creamy, hold the leaf by its stem. I like pinching it between my thumb and index finger and then using my middle and ring finger to support the leaf. Do what feels comfortable to you.

7. Dip your stirring spoon into the chocolate. Use the BACK of the spoon to spread the chocolate on the leaf. Make sure the chocolate is thick enough that it won’t break when you try to peel it. Place the leaves on the parchment as you work, and don’t let them touch.


8. The side of the leaf you use is up to you. If you are using mint and you put the chocolate on the back of the leaf, you will have some crazy patterns.  If you want something more subtle, use the front of the leaf. Coat the leaf almost to the edges. If you go too far, you will get ugly edges that are hard to peel. But don’t worry! Those leaves are the best to eat.

9. Put the tray of leaves in the fridge and wait a few minutes.


10. When the chocolate is set, peel the leave off the chocolate. You should have a perfect little mold of your original leaf. This may take a little practice. Work quickly as you have something designed to melt with heat in your hot little hands.

11. Done! You can store the leaves in the fridge until you are ready to use them. If the leaves got soft when you were working with them, put them back in the fridge to firm them up. Once they are firm, you can toss them in a plastic container.


Okay! So what’s the science here?

The word “chocolate” comes from the Nahuatl word Xocolatl for “bitter water,” referring to its original incarnation as a hot, spiced beverage in the Mayan and Aztec traditions. Traditionally, chocolate is a mixture of cacao powder, cocoa butter, and a sweetener. To make chocolate palatable and stable, we now mix milk solids, added flavors, modifiers, and preservatives.

Those candy melts? NOT CHOCOLATE! In this example, they are sort of chocolate colored, so they have that going for them, but they also come in a bunch of colors that are not known to nature so… not chocolate. They are mostly made of sugar and vegetable fats – not cocoa butter – and depending on the brand, they may throw in a little wax for better melting. Mmmmm… wax.

The advantage to the melts over the regular chocolate is that they do have the wax and the vegetable oil in them, which makes melting easier since the chocolate doesn’t need to be tempered. It hardens pretty quickly and sticks to whatever you dip in it, so it makes a great coating for cake pops or whatever crazy things show up on Pinterest this month.

Want to get super nerdy about your chocolate?  (I assume you do…) MIT has these tidbits available.

What’s in typical chocolate?

  • 10-20% cacao
  • 8-16% milk solids
  • 32-60% sugar
  • 10-20% cocoa butter
  • 2% theobromine and polyphenols

Cocoa Butter Chemistry

Fats and oils are organic molecules made up of three fatty acids chemically linked by an ester bond to glycerol. Fats are solid at room temperature, while oils are liquid.

Cocoa butter fats are made up predominantly by three major fatty acid molecules: Palmitic Acid, Stearic acid, and Oleic acid.

Oleic acid is unsaturated (has a double bond on its carbon chain), making it kinked and unable to pack well with other molecules. Because of this, a greater portion of oleic acid in the fat results in a lower melting temperature for the cocoa butter.

Chocolate makers can adjust the amounts of each fatty acid to produce a chocolate that melts only in the mouth, giving it a superior quality.

Tempering chocolate

The cocoa butter in chocolate can have several different crystal structures (three-dimensional patterns in which the fat molecules pack). There are six known chocolate crystal forms, or polymorphs. You can obtain each form by varying the fatty acid ratios and the temperature at which the chocolate is tempered (cooled).

Only a few of the polymorphs are considered good for gourmet chocolate because they give the right blend of snap (when you bite into the chocolate) and melting (when it warms up in your mouth). Melting is especially important because it controls how well the chocolate disperses and releases flavor onto your tongue.

Whether you will be constructing culinary masterpieces this fall or sitting back and enjoying the kitchen creations of others, we hope you have a happy holiday with you and yours!  (And when you’ve had a little too much togetherness, we will be open on Friday…)

Halloween How-to: Make a Spooky Skeleton Out of Recycled Milk Jugs!

Halloween requires skeletons. (And so does El Dia de los Muertos, for that matter…) If you’re on a budget but like to decorate, or you’re crazy about recycling, or you’re the crafty type who loves to add custom flair to everything, or you just want to see if you can do it, we’ve got a project for you!

Using recycled gallon and half-gallon milk jugs and some other simple materials, you can make your own reusable skeleton decoration to hang in your tree or around the house for spook season. Read through this easy procedure and watch our how-to videos for a clear example. Make one or make several, depending on how much milk your family drinks…


This homemade decoration is almost like the real thing! Photo by: Jason Schaefer


A minimum of nine plastic jugs – at least three of them gallon-sized


Hole punch

String, brads or pipe cleaners

Sharpie permanent markers or paint

Decorative bits (glitter, sequins, buttons, etc.)

Optional – High-temperature glue gun for punching holes


Three notes before you get started:

  • If you are making a second skeleton, you can probably use your jugs more efficiently than listed here and therefore need less.  If you are making this skeleton for the first time, I have asked you to provide 9 jugs (at least three of them being gallon-sized) so that you don’t have to work quite so hard to get a completed product.
  • The high-temperature glue gun works FABULOUSLY for punching the holes in the milk carton plastic, but I don’t recommend this method if you are a) working with younger children or are b) me because I absolutely burned myself. If you can get a volunteer in, they can sit and make the holes for the students pretty quickly.
  • If you are nervous about what you are doing, you can always sketch out your pieces with a Sharpie. Once you have them the way you want them, use rubbing alcohol to remove the Sharpie lines.
  1. Lay your hand or a template of a hand over the handle of one milk jug and trace.  Reverse the template or use your other hand for the second milk jug. Carefully cut the hands out. Save the extra bits.
  2. Repeat step one for the feet.
  3. Using a fifth and sixth jug, cut an extended oval out of jug around the handle, being as generous as you can with the oval. You can always trim it later! These will be the shoulder bones or scapulae. If you are clever, you can use the leftover bits to make your rib cage in step 9 as well.
  4. At this point, you should have two hands, two feet and two shoulder bones and a pile of left over bits.

    Where on the family tree would you place this skeleton? Photo by: Jason Schaefer

  5. Punch holes near the wrist portion of the hands and the ankle portion of the feet. Punch a hole in each end of the shoulder pieces.
  6. Using the leftover bits of your first six jugs, sketch out some bones. These should be basic stick shapes with lumps at each end. You will eventually need eight bones (four longer pieces for leg bones – two for each leg – and four shorter pieces for arms – two for each arm). Make them as long as possible. Once again, you can always trim them! In the example, my long leg bones crossed the jug diagonally to give them some extra length. With careful placement, I cut two long leg bones (and two knee caps) out of one of the leftover jugs.
  7. On a seventh jug, sketch out a skull (should consist of two large round eye sockets, an upside down heart or triangle for a nose and squares or ovals all lined up and touching for teeth). Use the two surfaces opposite the handle, and the jug should be upside-down. The neck of the jug will end up being the neck of your skull as well. You can add details as you see fit. It is also optional to cut the face out.
  8. Punch a hole in each side of the “neck” of your skull jug.
  9. Use your eighth jug to make a rib cage. You need to leave the neck of the jug as this will be the attachment point between the “hips” and the “ribs.”  That being said, cut out the handle of your jug so that there is a pretty big hole on one side of the jug.  This will be the front side of the rib cage. The neck and opposite side will represent the spine.
  10. To make the rib cage vaguely more accurate, cut some mostly horizontal strips out of the sides of the jug to leave the impression of ribs. The strips you cut out will become the empty spaces between the ribs. You will have to imagine that you are leaving a two inch vertical strip from the neck of the jug up the back to the bottom and down the front to the hole. This will act like the spine and the sternum. The horizontal strips you cut out should leave the two inch vertical strip intact.
  11. To make connection spots for the ribcage portion, cut two slits in the bottom of the jug on each side of the center. Then punch a hole on either side of each slit (for four holes total). Then punch two holes in the neck of the jug. If you are looking into the hole you created when you removed the handle, you will punch the one hole on the left of the neck and one hole on the right of the neck.
  12. To make hips, cut off the bottom of a ninth jug about two or three inches up. The example has a reinforced ring of plastic around the bottom and that was used to approximate the cuts. Round the corners of the jug and make the sides dip closer to the bottom of the jug.
  13. Punch holes in two opposite corners of the “hips.” 
  14. Cut a slit in the bottom of the “hip” piece and then punch two holes on either side of each slit (for four holes total). This is where you will attach your rib cage.
  15. Cut out two rounded corner squares from whatever leftover bits you have. These will be the kneecaps of your skeleton. Punch two holes in each that are opposite of each other.
  16. After you have everything cut out, you can make the parts interesting by drawing designs on all the bones in glow in the dark paint or Sharpie. Feel free to decorate your skeleton in either traditional Halloween or in the lighter and more decorative Dia de Los Muertos calacas style.
  17. Using a flat surface, align all the parts, making sure that you have the right connection holes punched out. Then connect all the parts together using the string, yarn or wire. Poke two holes in the top of the head and tie a loop that you can hang your skeleton from. From the top down, you should connect the pieces as such:
    • One shoulder piece to each side of the skull jug neck. Make sure they are facing the same way.
    • Tucking the ribs under the shoulder pieces so they stick out a bit, use the same skull jug neck holes to attach the rib cage. You will use the holes you created in the bottom of the rib cage jug to do this.
    • Connect your arm bones to each other and then to the shoulder.
    • Connect your hand to the end of the arm. Make sure they are facing the correct direction.
    • Connect the hip jug (bottom only) to the neck of the rib cage jug. You will use the four holes in the hip jug to connect to the two holes in the neck of the rib cage jug.
    • Connect the upper leg bones to the knee caps. 
    • Connect the knee caps to the lower leg bones.
    • Making sure they match, connect the legs to the holes in the side of the hip jug.
    • Connect the feet to the lower leg bones. Make sure they are facing the correct direction.


    Skulls, Horseshoes, Parrots and Robots: Fall Teacher Tuesdays offer awesome classroom ideas

    It’s officially fall, and I’d like to say the weather is cooling down and the leaves are turning bright and beautiful colors, but we live in Houston. So… no.

    Instead, I can tell you that we’ve been hard at work this summer developing fun, fast and hands-on activities for this year’s ExxonMobil Teacher Tuesdays. For adults only, Teacher Tuesdays offer fun and interactive professional development opportunities for ideas to kick your lessons up a notch. We’re pretty excited about the line-up this fall, and we’re dying to give you a sneak peak of what to expect.


    Our first ExxonMobil Teacher Tuesday has us focusing on one of our favorite topics: Day of the Dead! With all-new crafts, this workshop is sure to be a crowd-pleaser. Check out the photo above for a hint at the items we’ll be making in class. For those of you who have been to a Day of the Dead workshop before, you’ll be pleased to know that the sparkle box is back!


    In October, you can join us for an in depth look at the rock cycle with James Washington, Lead Concierge here at HMNS. James, who leads tours for the museum, has his very own collection of specimens he’s willing to share with the world. Anyone who has participated in what I refer to as “The James Washington Experience” leaves with a much better understanding of how all sciences are connected.


    You also have the opportunity to visit the new Hamman Hall of Coastal Ecology on Oct. 27 to discover the critters in and around the ocean. You’ll even get the chance to get up close and personal with a horseshoe crab. (Fun fact: horseshoe crabs keep you healthy in ways you probably don’t even know about but will learn in this mind-blowing workshop.)


    For November, pop down to the rainforest as you learn about the Amazon in the Out of the Amazon workshop. As part of the workshop, you will be treated to a rainforest wildlife presentation as well as a tour of the new exhibit Out of the Amazon. Dover and Frankie, our resident green-cheeked conures, might even make an appearance and will within minutes have entire room full of adults trained to do tricks.teacher7Join us in December for a viewing of Robots 3D in the Wortham Giant Screen Theatre. HMNS’s own Kathleen Havens wrote the curriculum for this National Geographic feature, so you know it’ll be hands-on, fun and engaging for students while covering STEM objectives and careers. If you’d like to discover some reasonable engineering challenges you can do at school for your elementary and middle school students that don’t require a $3000 grant, this workshop is for you!


    And that just takes us through December! The spring semester is just as exciting, covering everything from blood splatter to brain-based learning. Check out our complete schedule, and we’ll see you at HMNS!

    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…).


    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.


    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.


    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.


    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.


    * 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!!!!


    Individual serving containers of coffee creamer


    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



    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.


    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!