Purple, Green and Yellow: Marker Solubility

Purple, Green and Yellow by Robert Munsch

Brigid is a little girl in want of colouring markers, her mom isn't so sure.  Eventually Brigid convinces her mom to buy her some washable markers.  After a successful run with those, Brigid convinces her mom to buy her some scented markers.  And eventually, Brigid convinces her mom to buy her some super-indellible-never-come-off-till-you're-dead-and-maybe-even-later colouring markers. 

Brigid quickly learns about water soluble and water insoluble and your students can too.  In fact, your students can do Brigid one better and learn what makes those super-indellible-never-come-off-till-you're-dead-and-maybe-even-later colouring markers come off.

Place a paper towel over a short length of PVC pipe (or a small plastic container). 

Hold it in place with a rubber band. 

Students begin by using a water-soluble marker to make a circle on a paper towel. 

They then use a dropper to place drops of water in the center of the circle and observe.

Repeat this process using a permanent marker and water.

Finally, complete the process one more time using permanent marker and drops of rubbing alcohol. 

If time and budgets allow, students can create the Pinwheel t-shirts using the same process on shirts instead of paper towels. 

Snowflake Bentley: Sparkly Snowflakes

While both the book and activity have been featured on the Science Matters blog previously (here and here, respectively), it's been awhile and it's such a great pairing that it bears being part of this month's Picture Book Science.

Snowflake Bentley is a beautiful non-fiction picture book outlining the life of Wilson Bentley, the first man to photograph individual snowflakes. 

The highlights of Bentley's life are written as a child-friendly story.  Greater detail is provided in the margins of each page. 



This is a fun, artsy-craftsy project in which students can learn about solubility, super-saturated solutions and crystal shapes.  

Make a super-saturated solution of Borax and water:
--Fill a jar with hot water (boiling is best).
--Add Borax, a little at a time, until no more will dissolve (you'll know you're there because instead of dissolving the Borax will settle to the bottom)

Use pipe cleaners and thread to make a snowflake.

Attach a piece of thread to the snowflake.

Place the snowflake in the Borax solution and leave for several hours or overnight. 

In the morning, you'll have a beautiful, sparkling snowflake, covered with large crystals. 

If you'd rather not make snowflake shapes, you can shape the pipe cleaner into stars or other shapes.  You could also just place a straight pipe cleaner into the solution.

The pipe cleaner works well because all the fuzz on it gives the crystals nice places to attach, and thus works much better than just a string.  (Which may explain why all my attempts at making rock candy as a kid were met with utter failure (and a sticky mess)).


Safety Note: The Borax and the finished snowflake should come nowhere near the mouth.  

Summer Science Camp: Sharpie T-Shrits

This is both a Summer Science Camp idea and a previous-post update.

The pinwheel Sharpie t-shirts are a great summer science camp project.  Take the shirts, markers and rubbing alcohol outside and get creative.  Bonus: when you're outside there's less worry about alcohol fumes bothering anyone!

The update: when I was getting ready to do this project with a group of 24 students, I was trying to find some enough of the same type of container to stretch the shirts around, without making a huge investment. 

I decided to with with 4" PVC pipe (available from hardware stores), cut into 5 or 6" lengths.  You do need a hacksaw to cut the pieces, and the cutting can be a bit messy, so you'll have to determine if this option makes sense for you. 

It worked quite well for several reasons:

• The tie-dye designs don't usually go beyond 4", so it was plenty large.
• The smaller size (as compared to a shoe box or dish pan) made it easier for young hands to manipulate and stretch the rubber band around.
• The smaller size was nice for students sitting almost shoulder-to-shoulder at tables. 

The pictures included in this post are of shirts created by students in grades 3 through 5.

Solubility: The Floating Letter

Use a graphite pencil to write a letter (or other small figure) on one side of a sugar cube.

Place the sugar cube into a glass of water. (A white cup works best for visibility.  Or you could use a clear glass and place it on a piece of white paper).

Wait and watch.

The sugar will dissolve in the water, but the graphite from the pencil will not.  As the sugar dissolves out from underneath the graphite, the graphite will float the top of the water.

If you're lucky (and I'm usually not) the graphite will stay together and you'll have your letter floating on the surface of the water.  If it doesn't stay together, you'll just have small gray flecks floating on the surface (as seen above). 

Comparing Crystals

Note: I'm including this activity, even though I continue to struggle to get it to work myself.  I like the idea, and know that crystals can be grown from each of the following solutions, even if I can't grow them.  I can grow great Borax and Alum crystals.  The rest of them... not so good.  If anyone has any advice, please pass it my way. 

When leading a study of minerals, you'll talk about the repeating crystal structure of minearls.  Unfortunately, most mineral samples (especially those found in the classroom) don't provide students with the opportunity to see those crystals and the different shapes they can be. 

Consider making up a set of crystal sticks so students can see some of the different shapes crystals can take on.

Here's how you do it:

Make a super-saturated solution* of any of these solids in water:

--Table salt

--Rock salt

--Sugar

--Epsom salts

--Borax

--Baking soda

--Alum

Place a length of pipe cleaner into the solution and let sit overnight (or longer, depending on the solution). 

In the morning remove the pipe cleaners and allow them to dry.  Make sure you keep the nametags with the crystals, so you know which is which.

*To make a super-saturated solution:

Begin with boiling water in a jar.  Stir in as much of your solid as you can, until no more will dissolve and it starts to settle to the bottom of the jar.  You'll need a different amount of each solid to get the job done.

Sparkling Snowflakes

This is a fun, artsy-craftsy project in which students can learn about solubility, super-saturated solutions and crystal shapes.  

Make a super-saturated solution of Borax and water:
--Fill a jar with hot water (boiling is best).
--Add Borax, a little at a time, until no more will dissolve (you'll know you're there because instead of dissolving the Borax will settle to the bottom)

Use pipe cleaners and thread to make a snowflake.

Attach a piece of thread to the snowflake.

Place the snowflake in the Borax solution and leave for several hours or overnight. 

In the morning, you'll have a beautiful, sparkling snowflake, covered with large crystals. 

If you'd rather not make snowflake shapes, you can shape the pipe cleaner into stars or other shapes.  You could also just place a straight pipe cleaner into the solution.

The pipe cleaner works well because all the fuzz on it gives the crystals nice places to attach, and thus works much better than just a string.  (Which may explain why all my attempts at making rock candy as a kid were met with utter failure (and a sticky mess)).


Safety Note: The Borax and the finished snowflake should come nowhere near the mouth.  

Density Meltdown

This one is so very simple, but you can learn several things about density while watching.  

Fill a jar with vegetable oil.  Drop in an ice cube.  Watch what happens.

PS My apologies for not using an ice cube made of colored water.  But I think you can still see what's going on.  

Solubility Fireworks

Fill a tall bottle most of the way with water.

Place about a tablespoon of cooking oil in a cup.  Add a few drops of different colors of food coloring and stir them into the oil as best you can. (Limit yourself to one or two colors of food coloring - I used a bunch and it just ended up looking black - not what I was going for!)

Pour the oil onto the water in the bottle and observe.

There are a few lessons to be gleaned from this fun demonstration:
--Oil is less dense than water (i.e. it floats on the water)
--Food coloring is a polar substance, oil is non-polar (food coloring doesn't dissolve in the oil)
--Food coloring and water are both polar substances (food coloring dissolves in the water)

Chromatography: Pinwheel T-Shirt

Sharpie markers may not be soluble in water, but they are soluble in rubbing alcohol.  Use this property to your benefit to create some wearable art (and science)!

Place a dish pan or plastic shoe box inside a plain white shirt.  Pull the shirt taut and rubberband it in place.

Use the markers to make a ring of dots where you want the pinwheel to appear.

Using a dropper, drop rubbing alcohol into the middle of the ring. 

The alcohol will move outward, through capillary action, and carry the ink with it.

If the ink is made of a mixture of colors, you will see the colors separate.  If it's made from a pure color, you will simply see the color radiate outward.

Move the shirt on the box and make another pinwheel. 

Get creative...
...try making your ring of dots with a variety of colors
...what happens if you make your dots in a shape other than a circle?
...what if you start with one central dot?

How Does That Work: Doing the Back Float

This is a simple activity, but its explanatin is a bit sophisticated.  Therefore it's a good candidate for older and/or more advanced students.  But, don't let that stop you from trying it with younger students - keep your explanations basic and you might be surprised at what they take away from it.

What you'll need:

Baby oil

Water

Water bottle

Index card

Sharpened pencil

Hole punch

What to do:

Prepare a bottle, filled about half way with water and the remaining way with baby oil. 

On one side of an index card, color with a pencil, getting as much graphite as you can onto the index card.

Use a hole punch to punch the index card.

Place the hole punches into the bottle of oil and water.

What you'll see:
The dark side of the holes will always face the oil and not the water.  You can shake it up and they'll always return to that position.

Why:
Graphite is a good conductor, which gives it a negative polarity.  Water also has polarity, and it repels the graphite, so the graphite side will face the oil.


You can also talk about things like density, immiscibility and the like with this activity.

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How Does That Work is a series of products and demonstrations that you can present to your students and challenge them to explain the science of how they work. Make sure you decide ahead of time what you'll accept as a valid explanation - can it be printed straight off the internet, written in the student's own words, or does the student need to be able to explain it to you conversationally? What will a valid explanation earn the student - a prize, extra credit, a feeling of goodness?