Tag: homemade’

Flammable Science: Homemade Black Snake Fireworks

 - by KitchenPantryScientist

***Always wear goggles and fireproof aprons, if you have them, when working with flammable substances like ethyl alcohol, which burns very hot with no color! Be sure to pull long hair back as well!
Fireworks are really just explosive chemical reactions, and they’ve  been around for thousands of years. Most of them are far too dangerous to make at home, but with some parental supervision, it’s fun to make homemade “black snake” fireworks, which are basically just flambeed powdered sugar and baking soda! Thanks again to Pat Mullin of Labconco who sent me a video of this experiment, which I posted about a year ago.

I had to mess around with the recipe to get it to work consistently, and each time we do it we get different-looking snakes, but it’s pretty neat.  The key is to use enough fuel (alcohol) to keep your sugar burning.

BE SAFE!  Set this experiment up on a heat-proof surface like a concrete driveway and have a hose ready, just in case. Make sure long hair is pulled back, and don’t try this on a windy day.

You’ll need: 

1/3 cup sand, mounded in a pie plate with an indentation in the middle to hold the sugar/baking soda mix.

3 tsp. high-percentage alcohol (ethanol) like Everclear. I chose this as fuel rather than denatured alcohol or lighter fluid since there are no toxic fumes when you burn it.

4 tsp. powdered sugar mixed with 1 tsp. baking soda.

To make your snakes:
-Add the alcohol to the indentation in the sand.

-scoop 1 tsp. of the sugar/baking soda mix into a teaspoon and carefully drop it into the indentation in the sand.  It’s fine if it holds the shape of the spoon, but try not to pack it down!

-Have an adult use a grill lighter or a long match to light the alcohol around the sugar on fire.  It may be hard to see the flame, so stand back.  You’ll see the sugar start to bubble when it’s lit.  It will burn until the alcohol is gone, so wait until you’re sure it’s out before you try to touch the snakes!

What happens?  When the baking soda gets hot, it makes carbon dioxide gas. The pressure from this gas pushes the carbonate from the burning sugar out of the sand, producing the “black snakes” you see.

Did you know there’s carbon in plants, like sugar cane? It’s called new carbon and is constantly recycled between the environment and living things. There’s also old carbon, like the kind you find in fossil fuels, including coal and oil. Here’s a cool NASA video that talks about the carbon cycle:

Homemade Science Lab

 - by KitchenPantryScientist

Homemade science kits are fantastic, inexpensive holiday or birthday gifts. In addition, they’re great places to store loose science items you might already have around the house, like magnets or magnifying glasses. I’ll list how much some of the ingredients/stuff cost me at Target.  In a single shopping trip, it’s easy to  fill a plastic bin with enough supplies to do a number of science experiments (with a few last-minute additions from around the kitchen, like dish soap and milk.) The other morning, I talked about making your own science kit on Kare11 Sunrise.  Pair your kit up with KidScience app for iPhones and iPods, and watch your kid turn your kitchen table into a science lab! 

I’ll list some “ingredients” for science kits and link directly to the experiments in blue (just click on the experiment name.) You can print out directions from my website for older kids, or let younger kids watch the how-to videos on my website (see sidebar), so they can do them on their own. Better yet,  just put down some newspaper and let them start mixing things together.

Safety goggles, petri dishes,magnets, plastic test tubes, eyedroppers, magnifying glasses, plastic beakers and graduated cylinders are great additions to any kit! Many of these are reasonably priced at Creative Kidstuff stores, if you live in the Twin Cities.

Here’s what we put in our kit:

composition book: really cheap at Target and makes a great science notebook to draw, record, and tape photos of experiments into.
baking soda: $.52 at Target can be used for a number of experiments like fizzy balloons and magic potion. Mix with vinegar to make carbon dioxide bubbles.
vinegar $1.12 at Target can be used for fizzy balloons , alien monster eggs and magic potion.
balloons for fizzy balloons are $1.75 at Target.
dry yeast for yeast experiment is around $1. 32 at Target
white coffee filters: can be used for magic marker chromatography or making red cabbage litmus paper.
cornstarch: $1.27 at Target can keeps kids busy playing with Cornstarch Goo, a non-newtonian fluid. Here’s the video.
marshmallows around $1.50 at Target with rubber bands and prescription bottle rings you have around the house can be used to make marshmallow catapults. My kids used theirs to make their own Angry Birds game.
Knox gelatine and beef bouillon cubes can be used to make petri plates for culturing microbes from around the house. You can also use the gelatine for cool osmosis experiments!
Food coloring $2.39 at Target can be used to learn about surface tension by making Tie Dye Milk. Here’s the video. You can also easily make colorful sugar-water gradients that illustrate liquid density!
Mentos mints will make a Mentos geyser when combined with a 2L bottle of Diet Coke.
drinking straws$1.09 at Target are great for NASA soda straw rockets and a carbon dioxide experiment.
film canisters with pop-in lids make amazing rockets. I wouldn’t include the Alka-Seltzer tablets you need to make them work in kits for younger children, since they’re technically medicine. These rockets would be amazing gifts for kids to make each other.  They’re fun to make and decorate.

Decorating the bin with sharpies(or paint) and stickers is a great way to personalize it and fun for whoever is putting it together.  Have fun!

Homemade Petri Plates

 - by KitchenPantryScientist


Culturing microbes (bacteria and fungi) on petri dishes lets you test different surfaces for microbes and grow your own germs.  It’s also a great reminder of why it’s important to wash your hands.  Even very young children will have fun helping with the Q-tips and seeing what grows in their microbial zoo.  It’s fun, easy, and you might even already have what you need in your kitchen cupboard.  If not, the ingredients are readily available at any grocery store.

IMG_3658You will need disposable containers to grow cultures in (see below),  beef bouillon cubes or granules, plain gelatin or agar agar* (seaweed gelatin), water, sugar and Q-tips. (*Agar-agar can be found with Asian ingredients in some grocery stores.)

Note: Gelatin will melt if it gets too warm,and some bacteria make enzymes which can liquefy it, which is why scientists in labs use agar to make their plates.  The idea to use agar for plates originally came from the wife of a famous microbiologist who used agar for canning food. Try to keep petri plates away from hot lights, etc. so they won’t melt.

For containers, you can use foil muffin tins, clear plastic cups covered with plastic baggies, clear plasticware with lids, or real petri dishes to grow fungi and some bacteria.  We’re going to use clear deli containers, so that we can recycle while we learn.  (They look like they will be heat-resistant enough to pour warm agar into.)

You’ll start by making microbial growth medium (or germ food, as we like to call it.)

Mix together a little less than 1 cup water, one and one half packages gelatin (Or 1 and 1/2 Tbs. agar-agar), one bouillon cube (or 1 tsp. granules), and 2 tsp. sugar.  The next step is for an adult to help with, since it involves very hot liquid.  Bring the mixture to a boil on the stove, stirring constantly, or boil in the microwave, stirring at one minute intervals and watching carefully until the gelatin or agar is dissolved.  Remove the boiling liquid from heat and cover it with aluminum foil.  Let the growth medium cool for about fifteen minutes.


Pour the medium carefully into clean containers, until 1/3 to 1/2 full.  Loosely place lids, foil or plastic baggies over containers and allow dishes to cool completely.  The geltin or agar should make the growth media hard like jello.  When your plates have hardened, store them in a cool place, like a refrigerator, before using.  Plates should be used in 2-3 days.  When you are working with the plates, try to keep the lids on loosely whenever possible, so that they are not contaminated by the air.  If you’re planning to use muffin tins, simply place them in a muffin pan, fill them with agar, and when they’re cool, put them in individual zip-lock baggies.  With other containers, put the lids on tightly once the plates harden.

When the plates have hardened  and you’re ready swab, shake the condensation off the lids of the containers and put them back on.  Then, draw a grid of four sections on the bottom of the plate with permanent marker. (If you are using muffin tins, you’ll just label each bag with the surface you are checking.)  Decide which surfaces you’d like to test.  It’s always fun to label one section of the grid “fingerprint” to see what grows when you touch your finger to the plate.

Label each section with the surface you want to test.   Be sure to label the bottom of the plate since the lid will move.  You should be able to see through the agar to see your lines and your writing.  If you want to, you can label a separate plate for each surface, but we had three kids and three plates, so we made sections.  TV remotes, kitchen sinks, computer keyboard, doorknobs and piano keys are great surfaces to check.  You can even cough on a plate or leave one open to the air for half an hour to see what’s floating around!  (See the photo at the top of this post for a better picture of how your plate might look.)


Now comes the fun part.  Rub a clean Q-tip around on the surface you want to test.  Then, remove the lid from the plate and gently rub the Q-tip across the section of the plate labeled for that surface.  If you are careful, the agar shouldn’t break.  If it does, it’s no big deal.  When you have finished, set the plates on a flat surface with their lids loosened and taped on (do not invert them.)  I set our plates on a countertop where they wouldn’t be in the way.  Check your plates every day, and soon you will observes colonies of different shapes, sizes and colors starting to grow.


You will mostly see fungi (molds), but you may also see some tiny clear or white spots that are colonies formed by millions of bacteria.  Record and draw how your plates look in your science notebook.  Older kids can keep track of how long it takes things to grow and the shapes, sizes and colors of the microbial colonies that grow on their plates.  If you want to learn more about microbes, search for the words fungi and bacteria on the website cybersleuthkids.com and it will give you some great links to microbiology websites.  Microbes are everywhere, but that very few of them are harmful, and many of them are essential for good health.


Be sure to wash your hands after handling the plates, and throw the plates  away when you are done.  Remind your kids that if they wash their hands with regular hand soap for the length of time that it takes to say the ABCs, they’ll remove most of the harmful bacteria and viruses on them.  (For adults, a severe side effect of this experiment is the sudden urge to disinfect computer keyboards and remote controls.)

Here’s what grew on one of our plates: The large, fuzzy colonies are fungi and the small, whitish ones are probably bacteria.  The grid with the most fungi was cultured from our piano keys.  The one with both fungi and bacterial colonies visible was cultured from our bathroom sink.  One grid has mostly small, white bacterial colonies and was cultured from a water-glass my son drank from.  The fingerprint grid has only a single fungal spot.  My daughter must have washed her hands before touching it!  Our other two plates were pushed too close to the under-counter lights in our kitchen and the gelatin melted, so we threw them away.