The Best Black Slime Recipe Ever

For the most perfect black slime recipe ever, look no further! Say goodbye to grit and residue with this amazing deep dark goop!

Materials

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Procedure

  1. In one bowl, dissolve 1/2 tsp of borax into 1/2 cup of hot water.
  2. In the other bowl, mix 1/4 cup of glue with 1/4 cup water.
  3. A tsp at a time, mix 4-6 tsp of activated charcoal into the glue/water mixture. It won’t mix in at first, but just keep stirring, it will eventually mix in! Just a minute or so of stirring. Stop adding when it’s black enough for you. Mix until thoroughly combined.
  4. Add 12 tsp borax solution to the glue mixture a teaspoon at a time while stirring. This slow addition of the borax ensures a super smooth slime without the need for lots of kneading. You will know when to stop adding when all of the black glue mixture is in the ball of slime and there is none left in a puddle at the bottom of the bowl.
  5. Pick up the glob and fold and squish a few times. You’re done! After you’re finished playing with it, store it in an air tight container. If it feels gooey after a few days, add a little more borax solution till you get the consistency you like. We think this gradual goo-ing might be due to the activated charcoal absorbing some of the borax (see below for what borax does!).

Discussion

The glue contains a long molecule called polyvinyl alcohol (PVA). It is a polymer, which is a molecule that contains repeats of a subunit molecule (for example, “A” is a subunit and “AAAAAAAAAAAAAAA” is a polymer of A). Borax (sodium tetraborate) is a small molecule that can stick to parts of the PVA through hydrogen bonds. One side of the borate molecule can stick to one strand of PVA, while the other side of the borate can also stick to a different strand of PVA, creating a bridge between the two PVA strands. This is called crosslinking.

Having many crosslinking sites usually makes a polymer more rigid, but the interesting thing about borate/PVA crosslinking is that the bond is transient, meaning it can easily break and reform somewhere else. This causes the slime to act kind of like a liquid and kind of like a solid. If given time, the PVA can ‘flow’ as gravity pulls and breaks the borate/PVA crosslinks. It acts like a slime instead of a true liquid because as the PVA molecules pass by more borate, they can momentarily bond to borate and another strand of PVA, slowing down the flow. If you pull the slime fast, you break all those bonds quickly, allowing the slime to act like a solid momentarily.

This dark black slime is perfect for Halloween. Throw some googly eyes, plastic spiders, or confetti in there for hours of fun!

See Sound with Oobleck!

This is a fun, silly, and educational activity that any kid who likes to make noise will love. Using oobleck (a mix of cornstarch and water) and common household items, you will be able to visualize the sound waves made when you yell!

What we perceive as sound is a wave of pressure transmitted through air. When you yell, your vocal chords vibrate. The energy is transmitted by air molecules smacking into each other, until they they smack into your ear. There, you have cells that can convert the vibrations into electrical signals which are transmitted to and deciphered by your brain. In this activity, you will yell into a device that will transmit your sound waves from air into oobleck so you can see the waves!

Definitions

  • SOUND: Kids will probably know what sound is, but not scientifically. Sound is vibrations that travel through a medium (usually air) which are eventually heard by ears. Kids will need to understand that air, even though we can’t see it, is all around us and can be moved similarly to the way balls move, like billiards. Try waving your hand quickly so they can feel the wind it creates. You can tell them air molecules can move to carry the energy from your hand to their skin so they can feel it. Sound also travels through air in a similar way, but sounds are made when something is wiggling the air much fast than your hand can move it. Roll a ball into another ball and talk about how the energy is transferred when the first ball hits, and use this analogy for air transmitting sound.
  • VIBRATION: To young kids, I like to explain this as fast wiggles. Since you know your kid the best, to define this word, you can draw on experiences you know they have had like the vibration of an old car going down the highway. You can also put their hands on one end of a table and have them feel the vibration of you knocking at the other end of the table. They probably have experienced vibration, but just need to connect the word with the phenomenon.

Materials

  • cornstarch
  • water
  • empty paper towel or toilet paper tubes
  • tape
  • rubber bands
  • thin flexible material like plastic wrap, latex, thin rubber sheet, nitrile (I cut a square from nitrile gloves)

Method

  1. Cut the paper towel roll twice diagonally, as seen in the picture.Untitled_Artwork
  2. Flip the two end pieces up to form a U shape, then tape them together. (Or make into whatever shape you want. You basically want to be able to simultaneously yell into it and see the flexible membrane. The one below is what my daughter made from toilet paper rolls.).IMG_4134
Clearly, it doesn’t have to look pretty.
  1. Cut your thin flexible material into a square that will fit over the end of the paper towel tube.
  2. Secure the square to the tube with a rubber band, making sure the membrane is taut like a drum.
  3. To make the oobleck, mix about 2:1 cornstarch to water together (you can make a lot to play with it later, but for this activity, you only need about a teaspoon). You will know it’s the right consistency when you can smack the oobleck and it acts like a solid, but you can also slowly pour it as if it was a viscous liquid. Just add a little more cornstarch or water to get this consistency.
  4. Put about an eighth teaspoon of oobleck onto the drum end.
  5. Make all sorts of sounds into the open end of the paper towel roll and watch the oobleck dance about! Constant, steady low or high sounds work the best, but experiment to see what you can make!

Discussion

When you scream into your device, kinetic energy is being transferred from your vocal chords, through the air molecules in the tube, to the membrane, to the oobleck. Note how the oobleck is formed into different shapes depending on the pitch of your noise.

You can use this experiment to talk to your kids about eardrums (aka tympanic membrane) by comparing them to the membrane on the device. Just as the screaming-device-membrane transmits sound from air in the tube to the liquid oobleck on top, your eardrum essentially transmits sound from the air in the ear to liquid in the cochlea.

512px-Anatomy_of_the_Human_Ear_en.svg
A diagram of the anatomy of the human ear. Lars Chittka; Axel BrockmannPerception Space—The Final Frontier, A PLoS Biology Vol. 3, No. 4, e137

This project can also be done by wrapping a speaker in Saran Wrap, putting some oobleck on it, and playing your kids’ favorite songs. It’s a great visual introduction to rhythm, beat, and volume and will give them a whole new musical experience.

Make your own painting Art-Robot: Inspired by “Ada Lace Sees Red”

One of the best ways to bring a new activity into your kid’s life is to be inspired by a special book. After reading Ada Lace Sees Red, (SPOILER ALERT) which features a robot that can paint (and an intelligent heroine), my daughter couldn’t get enough, so I thought I’d expand her love of the book by helping her make her own art-bot.

This project uses a vibrating motor to wiggle a cup attached to paint brushes. Other variations of vibrobots include bots that vibrate a scrub brush (bristlebots) and bots with markers for coloring!

Anna really likes taping things.

Materials

Note: Instead of using a motor with a nut, you can alternately just buy a vibrating motor. I prefer making it from a normal motor because we can also use the motor for other things that don’t involve vibration, whereas vibrating motors can only be used for vibrating things.

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Procedure

  1. Securely tape the bolt nut to one side of the motor shaft. As the motor spins, the nut will cause it to be unbalanced, making the whole thing vibrate.
  2. Hook up your circuit (including a switch if you would like). Be sure to follow the directions on the motor you purchase, as incorrect wiring can cause things to get hot or spark.
  3. Add the battery and test your motor, making sure the nut is securely affixed so it doesn’t fly off.
  4. Flip the cup upside-down and tape 3-4 paintbrushes around it so it can stand up on the brush ends (see picture above with markers as an example).
  5. Tape the battery terminal and motor to the cup, ensuring the nut has room to move around.
  6. Test out your bot to make sure everything is affixed securely.
  7. Dip the brushes into paint, put it on paper, then turn it on!

This can also be done with markers, which are less messy than paint, or crayons, which are even less messy than markers. After you’re done making art, try attaching your eccentric motor to something else, like a scrub brush or dry mop!

Book Inspiration- Ada Lace: Sees Red

From the publisher:

From Emily Calandrelli—host of Xploration Outer Space, correspondent on Bill Nye Saves the World, and graduate of MIT—comes the second novel in a brand-new chapter book series about an eight-year-old girl with a knack for science, math, and solving mysteries with technology.

Ada Lace is building a new robot! She’s determined to beat Milton in the upcoming robotics competition. But she’s distracted—Ada finds her dad’s art class impossible, while Nina is the star of the class, basking in the glory of being Mr. Lace’s star pupil.

When Mr. Lace suggests that Nina put on an art show, Ada becomes jealous and loses her temper. Now Ada isn’t speaking to her dad, she’s falling behind in art class, and she still doesn’t know how to fix her robot. As the competition looms closer, Ada starts to wonder if there might be a way to use both science and art to solve her problems.

Will Ada make up with her father in time to test her hypothesis? Or will her hurt feelings leave her seeing red and without a medal at the end of the day?


Ada Lace Adventures is a series about a girl who uses science to help solve problems and mysteries. It is intended for readers ages 8+, but I read them a chapter at a time to my young daughter. The books are not in-your-face nerdy at all, as Ada is just an ordinary girl who likes science. I like that these books counter the stereotypical dorky science character that we frequently see. They are well written, fun to read, and a great addition to your chapter book library.

Color Changing Lava Lamp

 

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One of my goals is to create simple science projects and demos that parents, caregivers, and teachers can easily perform using everyday supplies. I love this color changing lava lamp because it does exactly that. It illustrates so many concepts of chemistry, has ingredients you might already have (or can easily grab from the grocery store), and it is quite frankly AWESOME. So pour yourself some red cabbage juice, oil, and Alka-Seltzer and watch the science happen!

Continue reading “Color Changing Lava Lamp”

Extract your own DNA!

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Did you know extracting your DNA so you can see it with your own eyes is one of the easiest science projects you will ever do? Take a look at the video below and try it out for yourself! We’ve also included some cartoons from The Baby Biochemist: DNA to illustrate what is happening during each step!

Continue reading “Extract your own DNA!”

How to Make Bendy Bones

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If you ask most kids what bones are made of, they would quickly answer “calcium!” Though it’s not incorrect, years of us telling them to drink their milk for strong bones has hidden an amazing feature of nature, biomineralization by proteins. Calcium is only half the story of bones. Though the semi-crystalline mineral that contains calcium, oxygen, hydrogen, and phosphorus, called hydroxyapatite, provides strength and rigidity, our bones also need to be elastic to help absorb shock. This is where proteins come in. Your bones are made of living tissue that spew out networks of protein that trap and crystallize the calcium in your body. Together they form the strong, resilient biomaterial we know as bones.

You can feel the flexibility of the protein network for yourself by reacting and dissolving the hydroxyapatite from the bones in vinegar. What’s left are entertaining, wiggly bones the kids will love to play with (except my daughter, who was too grossed out and didn’t want to touch them which is why all these pictures are of my hands ¯\_(ツ)_/¯ ).

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Magnetic-Tile Circuits

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This project is for ages 3+ as it uses small parts which are 
dangerous when swallowed. Supervise young children.

Ready to make an already awesome toy even more awesome? All you need is less than $20 in special supplies (copper tape, LEDs, and button batteries), tape, scissors, and some magnetic tiles to start to snap together basic circuits.

If you don’t have magnetic tiles, you can also use these same supplies to make paper circuits.

Continue reading “Magnetic-Tile Circuits”