A favorite ooey gooey sensory bin idea around our house is oobleck. Oobleck is a non-Newtonian fluid so under pressure (hitting, squeezing, or jabbing) it acts like a solid. In contrast if you’re gentle with it (resting a finger on it’s surface or holding it in cupped hands) it acts like a liquid (finger sinks in or the oobleck flows out of your hands). Lately the kids have enjoyed making it themselves so it’s been a bit more watery although still a lot of fun. I blogged about this two-ingredient sensory material before then later changed it up by freezing it and using it in a fun color mixing sensory bin at Ada’s birthday party last year. Recently, while packing to move, I had an almost empty Costco-sized container of cocoa powder and decided to change it up again and created muddy oobleck.
While making the muddy oobleck I gave each kid a box of cornstarch to dump into their sensory bin along with a spoon so they could mix it up and play with it. I then gave them each a cup with water so they could create their oobleck themselves. I tried to keep the overall ratio to two parts cornstarch and one part water but Zoey didn’t mix it all together and Ada wanted more water added to it later on, so both of their oobleck looked runnier than normal. After handing out the water I then split up the cocoa powder between the girls. If I were to redo this I would split the cocoa powder between two dry cups and, after they mixed it with the cornstarch, refill their cup with water.
They were restricted in the amount of cornstarch and cocoa powder they were given but if they wanted it runnier I would happily refill their plastic cup with water. Ada loved repeatedly filling her cup and then dumping it on her arms calling it “sun screen”.
Since I let the kids choose how much water they wanted, and I was dumping out the rest of the cocoa powder, I don’t have measured ratios for you. When making plain white oobleck myself I try to stay close to two parts cornstarch and one part water. Quickly looking up cocoa powder oobleck online while writing this up I came across ‘Muddy Monster Truck Derby Sensory Bin’ on Mama.Pappa.Bubba if you want a runnier muddy oobleck and a ‘Chocolate Oobleck’ on Teaching Mama if you want a more oobleck-like mixture.
At some point the kids started getting tired of the bin so I extended the play by dividing up the last of a container of salt between them. I put the salt in their cups so they could add it in their own time. Ada ended up filling her salty cup up with oobleck before adding later dumping it in the bin while Zoey dumped it in right away. Once they started getting bored I grabbed our two Dollar Tree monster trucks for them to each play with in the mud.
Zoey ended up being done playing first so Ada got to add Zoey’s monster truck and oobleck to her bin while I moved Zoey over to the kitchen sink. Even though she was done with oobleck Zoey decided she wanted to play in the sink so I filled her emptied bin with soapy water and limited her to the more child-safe dirty dishes by the side of the sink (prewashing my dishes for later). Once Ada saw what Zoey was doing she requested soapy water so I grabbed another bin so she could dirty up her monster trucks before washing them… again and again.
When it comes time to clean up I’ve never had a problem pouring it down the sink although the kids have been diluting it first and I still make sure to run water at the same time so it’s extremely diluted. For regular oobleck I normally throw it out since it isn’t too liquidy. While writing this I wanted to confirm for clean up and found a Home Improvement Stack Exchange question where a clog formed when their daughter dropped oobleck in the drain without diluting it first. On that thread someone mentioned never using hot water to unclog since that will “cook the starch and turn it into a giant gravy lump” whereas the only answer had you fill your sink with water so you can use a plunger on it and if that fails it probably got stuck in the p-trap which needs to be removed and cleaned. If you want a tongue in cheek answer to if it ever plugs XKCD has delivered by giving a scientific answer to a reader’s hypothetical question: “how much cornstarch can I rinse down the drain before unpleasant things start to happen?”
I love how adding simple cocoa powder gave the kids a new lease on their oobleck. I’d love to know if you made some and if you chose to make actual oobleck or if you added more water to make it more like mud. I’d love to hear what you added to your sensory bin to make it your own. Feel free to share in the comments below, on my Facebook page, or through Instagram. I hope you’re having an awesome day!