Buried Treasure in Oobleck

Here's your nightly math! Just 5 quick minutes of number fun for kids and parents at home. Read a cool fun fact, followed by math riddles at different levels so everyone can jump in. Your kids will love you for it.

Buried Treasure in Oobleck

September 15, 2014

Ahoy, Buccaneers! Are ye ready for the big day? Talk Like a Pirate Day is just around the corner, September 19. Our Pirate Printable is full o’ fun fer yer crew.  Avast me hearties, I uncovered a bit more o’ the good stuff fer ye. By that I mean ye lads and lasses are going to uncover treasure buried in oobleck, which is muckier than the quicksand I got me leg stuck in on that last treasure hunt.

Phew. This talk like a pirate thing is tough! Let’s move on to the activity.

Make the Oobleck

Oobleck is a mixture of cornstarch and water mixed in a ratio of 2:1. Plan on at least ½ cup of cornstarch per child. So for one child mix ½ cup of cornstarch with approximately ¼ cup of water in a small bowl. It looks like a simple recipe, but oobleck is anything but simple- it’s a non-Newtonian fluid. That means it has properties of both solids and liquids. It’s crazy fun and a sensory delight!

How can you tell if you have the right mix? The contents of your bowl should react like a solid in response to pressure. Tap the surface hard and fast. Does it feel solid? If not, add a bit more cornstarch a sprinkle at a time and mix it up. Next, gently rest a finger on the surface of the oobleck. Does it sink down?

Oobleck is fascinating. Scoop up a handful and press it tightly in your fist to make a ball. After you’ve got a nice compact ball, relax and open your hand. Watch the ball melt away, dribbling through your fingers.

Bury Your Treasure

Toss a coin into the oobleck with some force and observe how it is slowly absorbed into the mixture. Now gently place the coin down and see what happens? What other factors affect interaction of the oobleck and the coins? Do you think each coin’s mass affects it journey down through the oobleck?

According to the US Mint, here’s the mass of common coins:

  • Penny 2.5 grams (g)
  • Nickel 5.0 g
  • Dime 2.3 g
  • Quarter 5.7 g

Maybe coin density plays a role?

Sinking penny in oobleck from www.BedtimeMath.org

Let the Treasure Hunt Begin

Now that your coins are good and buried, give each little pirate a chance to fish out a coin one at a time until the all coins are gone. If you used different denominations, add up the coins to see who has the highest total. If you used one type of coin, a winner can be determined based on the year the coin was minted. Who has the oldest? The newest? Whose coin was pressed closest to their year of birth? There are many options for bringing numbers into the conversation

Variations

You can use small beads, buttons or coins as hidden treasure, too. These options open up a whole world of math as you ask the kids to assign values to the different sizes or shapes. Who wouldn’t value a shiny, plastic gem at $1,000,000?

Properly covered, the oobleck will stay fresh for a few days. Be sure to dispose of it in the trash, oobleck is bad for your plumbing, so don’t send it down the drain!

Forget about talking like a pirate, do math like one with this Bedtime Math problem

Photos courtesy of Kim Moldofsky

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About the Author

Kim Moldofsky

Kim Moldofsky is a mom of teen boys in the Chicago area. She blogs at TheMakerMom.com and hosts a the popular monthly #STEMchat on Twitter where parents and educators share ideas and resources to raise STEM-loving kids.

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