A Science Trick to Try at Home

Instructions from Margriet Ruurs

You -- yes, you, right there -- can turn two solids into one liquid. It's not magic. It's science.

How can you turn a solid substance into a liquid without adding any liquid? Here’s a fun trick to try at home. All you need is a spoonful of sugar and some fresh yeast. You can buy fresh yeast at any bakery.

Instructions:

Fresh yeast. Image by Hellahulla, from
Wikimedia Commons

• In a small bowl put a small slice of the fresh yeast.

• Sprinkle a spoonful of sugar on top.

• Just let it sit for a few minutes. You’ll notice the yeast turning darker.

• After a while, take a teaspoon and stir the two solid materials. 

You’ll find that both solid ingredients have turned into a liquid all by themselves! This process is called osmosis.

White sugar is made up of solid crystals -- until the crystals
meet the moisture in the fresh yeast.

The sugar crystals dissolve because of the humidity (dampness) in the fresh yeast, forming a highly concentrated sugar solution. But the sugar concentration inside the yeast cells is low.

The liquid containing a large amount of sugar has a natural tendency to mix with the liquid that has less sugar and even out the sugar concentration. The yeast cell membranes separating the two solutions aren't strong enough to overcome that force, so the membranes break down. Then the water inside the cells bursts out. Pretty soon, all the sugar is completely dissolved in the released water.

And presto! -- Osmosis has turned your two solids into one liquid. It's a little magical, but it's science magic!

What Makes an Octopus Blush - and How Exactly Do They Do It?

Posted by Helaine Becker

We've all heard about octopi that can change color to mimic their environment. But how do they do it? I discovered the answer when writing The Big Green Book of the Big Blue Sea for Kids Can Press.

The book is designed to present information to kids ages 8-12, but also to engage them with cool hands-on (or do we call that "experiential" now?) activities. Most people learn best by doing, and doing stuff that involves splashing water is pretty well a can't-fail learning opportunity.

The problem with octopi, though, was that I couldn't find a good activity anywhere out there to explain color-changing skin. I had to invent one.

Coming up with ideas is pretty easy for me. But coming up with ideas that any klutz, I mean kid, can do (And I am the klutz in question; if I can't do it successfully, it won't go in the book) wasn't a piece of cake. Luckily, cake was not required. Waxed paper and food coloring, however, were.

For all you lucky readers, here, in it's entirety, is the activity I invented. You'll find it, and many other fun and kooky things to try and do in The Big Green Book of the Big Blue Sea. Check it out, please!



 Seeing Spots?

Make your own octopus skin in less time than it takes an octopus to blush.

Image courtesy Pamsclipart.com

You Will Need

a large sheet of newspaper 

2 sheets of waxed paper about 30 cm (12 in.) square

yellow food coloring

1.     Lay the newspaper on your work surface to protect it.

2.     Lay down one sheet of waxed paper. Can you see the grayish newspaper through it? That’s the color of your octopus skin.

3.     Staying away from the edges of the waxed paper, carefully place 10–20 drops of food coloring on the waxed paper about 1 cm (½ in.) apart. Can you still see the gray newspaper between the colored dots?

4.     Hold the second sheet of waxed paper above the first sheet. Gently place it on top of the first sheet. See how the spots seem to spread out? Gently press on them with your thumb to spread them out even more. Can you still see the gray newspaper? Or does your octopus skin look yellow?

5.     Lift the top sheet of waxed paper off the bottom sheet. Do the dots return to their original size?

What’s Going On?

An octopus can change color to hide from prey or predators by blending into its surroundings. Many scientists think octopus also use color to communicate and express emotions, such as fear or dominance.

But how do our wriggly friends achieve this tint-o-riffic trick? Octopus skin contains microscopic pigment-filled structures called chromatophores, represented here by the dots of food coloring. Real chromatophores are so small, you can’t usually see them.

When an octopus wants to change its hue, it changes the size and shape of its chromatophores. Your thumb, forcing the dots to expand, acts like the small muscles in the octopus’s skin. They pull on the chromatophores to widen them. Now the skin they’re in is filled with color!

When the octopus relaxes, the chromatophores shrink back to their normal size. The octopus’s skin returns to its original color.*

*Excerpted from The Big Green Book of the Big Blue Sea, Copyright 2011 by Helaine Becker, Kids Can Press, Publisher. All rights reserved.

The Big Green Book of the Big Blue Sea

 Posted by Helaine Becker

We know the ocean is at risk. Rising global temperatures, deoxygenation, and increasing acidity are all serious threats to marine ecosystems. Knowing these facts, it’s easy to fall victim to despair.

But there is reason to hope – lots of it. And that’s one of the inspirations for why I wrote The Big Green Book of the Big Blue Sea, my new book from Kids Can Press.

It’s an experiment-based science book that teaches kids through first-hand exploration how different aspects of the marine system work – why ice floats, how currents form, how fish swim. It also gives kids a chance to explore environmental issues, like the enormous garbage island in the middle of the Pacific, or how an oil boom works.

But The Big Green Book of the Big Blue Sea is more than an experiment book. It’s also a primer on the threats facing the ocean. And most importantly, it’s a serious discussion of what people today, all over the world, are doing to protect the sea and minimize the impacts of human activity.

We all know that the media focuses on negative stories. They are immediate adrenalin-boosters, and feed into the human need to constantly scan the horizon for danger. But that focus on risk means we don’t really hear the other half of the story – we don't hear about the car that didn’t crash or the lost wallet that was retrieved.

This is true when discussing environmental issues too. We hear about the coral dying, the sharks being finned, and the Dead Zones expanding. But few ordinary people realize that Dead Zones have also disappeared. That corals can be regrown. And that new laws across North America are in place that will help protect our seas well into the future.

The Big Green Book of the Big Blue Sea presents it all: the facts, the risks, and the heartening stories of recovery.

Some of the facts may surprise you –like learning pearls are NOT caused by bits of grit that get caught in the oyster’s shell!). Some may delight you – like discovering how the beluga whales of the St. Lawrence River are no longer in danger of extinction, thanks to a concerted effort by Quebec’s citizens and business community. Some may even astound you. But in the end, you (and your students) will discover the ocean is larger, more complex, and more diverse than anything you could have ever imagined.

The truth is the ocean is under serious threat. We can’t be Pollyannas, pretending there are no problems. But we also can’t be Eeyores, seeing nothing but doom in our future. The reality is more nuanced. There are many reasons for optimism.

Optimism, I think, is a requirement for children’s non-fiction. To tell young people, “all is lost” is counter-productive. It negates them, and their future. It  also, plainly, is false; it's unsubstantiated opinion.

The facts point in the other direction. Where there is life, there is hope. And there’s lots of life in the ocean: More, in fact, than anywhere else on the planet.  Resilient, adaptaive, wildly creative life.

Shouldn’t that fact alone give us reason to hope?