Sunday, October 24, 2010

The Floating Safety Pin

The first thing you should do is bet your friends that you can make a safety pin float on water.  When they say you're crazy, just follow the simple steps below to prove them wrong.  Surface tension is on your side, you just need to know how to use it.

What you need:  A dry safety pin; a paper towel square (2 in. x 2 in.); a bowl of water; a pencil or a small stick

What to do:  Fill the bowl with water.  Then put the paper towel on top of the water and spread it out so that it's flat.  Next, carefully place the safety pin on the paper towel.  Use the pencil or small stick to gently poke the paper towel until it sinks from beneath the safety pin.  If you did this carefully enough, the pin should remain behind floating on top of the water.  Amazing!

How does it work?  Even though the safety pin is more dense than water (which makes it want to sink), a force exists at the surface of the water, called surface tension.  Surface tension is created by attraction of individual water molecules to each together.  As long as some turbulence or vibrations do not disturb the surface tension, the pin will float.  A water strider makes use of surface tension when it moves across the surface of a quiet pond.  Its tiny mass and the geometry of its legs allow it to be supported by the high surface tension of the water.

This activity is suitable for just about anyone who wants to try it, but it does require some care and a gentle touch.  A teacher might be able to provide the biggest "wow factor" by first asking the class to try to get their safety pin to float on their own, and then showing them how to do it.  Of course, a nice discussion of surface tension can follow.  Thanks to Vinh Nguyen of U.T. Arlington for submitting this activity to DISCUS. 

Tuesday, October 19, 2010

Find your Footprint with National Geographic

A great opportunity for teachers and students to learn about sustainability and the impact they are making on the environment.  How will you measure your footprint?  The deadline for this competition is December 3rd, 2010.

Students will learn about their own "footprint" so they can make a greener world and a greener school, as they develop a project to submit to National Geographic for judging. The campaign also features educational resources and a lesson plan on saving water, saving energy and reducing waste.

Contest: http://www.nationalgeographic.com/findyourfootprint/enter/
Prizes: http://www.nationalgeographic.com/findyourfootprint/prizes/

Sunday, October 17, 2010

Inflate a Balloon on a Bottle

Blowing up a balloon on your own can be a hassle...the balloon tastes weird and sometimes it is tough to stretch the balloon out.  I'm not exactly Billy Mays, but I'm going to try to sell you this great new way (OK, it's not new, it's a reaction as old as time) to blow up a balloon that removes all of the hassle of having to do it yourself.  It's safe, fun, easy, and you could just learn a little science along the way.  For only $19.95...nevermind, it's cheap and you probably have everything you need at home to do it yourself already.

What you need:  a bottle (16 oz - 2 L, as desired; if you use a small bottle, you might want to use less of the key ingredients); funnel or butter knife; balloon; 3/4 cup white vinegar; 2 tbsp. baking soda

What to do:  Transfer the baking soda into the balloon using a funnel or the butter knife.  Add the vinegar to the bottle.  Carefully attach the balloon to the top of the bottle without letting any of the baking soda fall into the vinegar.  Once the balloon is securely attached, tip the baking soda into the vinegar and watch as the reaction proceeds.  Vigorous bubbling can be seen in the bottle as the balloon fills with gas. 

What happened?  What you saw was a rapid chemical reaction.  Baking soda (sodium bicarbonate) is a base and vinegar (5% acetic acid) is an acid.  When this acid and base are mixed, they react to form water, a salt, and carbon dioxide (the gas).  The carbon dioxide builds up pressure in the bottle and inflates the balloon.  Try different amounts of vinegar and baking soda to see what combinations create the most gas.  Record the amounts of ingredients you use and your observations (you can record how big the balloon is by measuring its circumference with a measuring tape...or a piece of string and a yard stick).  Try keeping a science notebook for this and other cool experiments.  That way, you'll always remember what you did, so that you can show off for your friends.  For teachers, this activity can be used as part of a lesson on chemical change, stoichiometry, acids & bases, or many other topics.

We recommend this activity for elementary to middle school students.  If necessary, have your parents help you measure the ingredients and attach the balloon.  Thanks to Sabra Ramirez of U.T. Arlington for submitting this activity to DISCUS.  Sabra credits "Exploring Creation with General Science" by Dr. Jay L. Wile for the preparation and demonstration of this activity.

Have You Thought About Your Teaching Philosophy, Lately?

We are continually asked to set goals for our students, figure out how we are going to get each and every student across the finish line, but how often do you think about your own goals? Back when you were an undergrad you more than likely received an assignment to write a teaching philosophy, but that was before you were in the classroom. Maybe nothing has changed from those views, maybe they have changed so drastically you could benefit from blowing the dust off of that old assignment and rereading your own reflections, but more than likely you need to sit alone for a while and simply reflect on what you have learned from the past years, what works for you, and how can you express that in your own teaching philosophy. My challenge to you is to take the time to reflect and put your own teaching philosphy into words. It will bring back the excitement you felt when you first chose teaching as your profession, it will positively enhance your PDAS review; but moreover, it will define your most essential goals so you clearly understand why you do this job and the rules you prefer to live by in your own classroom. Everybody seems to emphasize different aspects of the job. When I recently rewrote mine, of course I viewed it numbered like a scientific procedure in my mind, so that's the way it went down on paper and I love it. I glued it on bright purple paper and posted it above my desk. I decided I wasn't going to laminate or frame it because I always want to reserve the right to think and change it if I choose to. Strangely, mine was very similar to my undergrad assignment, except I could not rank the importance of their order like I can today. What would yours look like?

My Philosophy of Teaching

Looking back over my years of teaching, I initially became a teacher because I thought it would be the best way I could make the world a better place. However, as time has passed, I still hold this ideal close yet have concluded there are seven personal guidelines which have molded me into an outstanding teacher.

Guideline 1: Make it significant. “Why do I need to learn this?” resonates from the mouths of students in classrooms today. As their chemistry teacher, it is my duty to ensure my students see how chemistry surrounds them in every aspect of their life. From the chemistry of fireworks, electrons producing light, ionic compounds and electrolytes needed for proper hydration on the football field, my students understand the relevancy of chemistry in their world. The labs and activities I choose to do with my students are intentionally chosen to enhance relevancy to my current group of kids.

Guideline 2: Make the kids laugh. I honestly feel laughter is a powerful tool in learning which is all too often quickly dismissed by even the finest of teachers. I quickly learned my students need to trust me and know I am emotionally invested in their success. Laughing is a crucial aspect of this bonding experience. I believe if you make them laugh, you get their attention in the process. They become emotionally connected and invested in the material and suddenly, like magic, permission is granted to teach and they will learn. Be cautious with this guideline, though, because more times than not they will make you laugh uncontrollably.

Guideline 3: Make learning fun and inclusive. Our class periods are 90 minutes long. In order to keep the attention of the students and to use every minute of class time, one must be creative. Creative techniques come in many forms. Sometimes labs are appropriate, other times there are hands-on activities, simple demonstrations, or activities which get the kids up and about, and most of the time, the use of technology is required. I love to use my Promethean board interactively with my students. Letting them interact, choose their own colors, and work problems allows the class to bond and become responsible for each other’s learning.

Guideline 4: Have high expectations. I have learned that children will rise to whatever expectations you set for them. Striving to push the kids to learn more and do more than they have ever expected of themselves is a very rewarding experience. Many expect students would love having a class that is an easy one. This is only true for a few weeks. Each year, when I encounter former students, I am always proud to hear them say, “I love Mrs. Cruze’s chemistry class. Even with the most difficult material, she made it so easy to learn!”

Guideline 5: Always try new things. This is a very important guideline more for me as the teacher than the students. To keep things new and exciting, it is imperative to frequently attend conventions, collaborate with other teachers, and research new ideas. This keeps the curriculum current as well as challenging for the teacher. Every year, I make an effort to change our hands-on activities, experiment with new project ideas, and try out new laboratory investigations.

Guideline 6: Be sure to share. On my kindergarten diploma, it says “You have graduated from kindergarten because you have shown the ability to share and play well with others.” This is one of those life guidelines which should have been ingrained in our brains since those early days in the sand box. Share everything! If you find a cool activity online, share it. If you make a new presentation, share it. If you create a new lab or game, share it. The benefits of sharing are immeasurable because when you share, even more students will benefit in the long run, and that is what matters.

Guideline 7: In my opinion, this is the most important guideline of all. The relationships you develop with your students are more important than anything else. The kids can tell if you enjoy what you do, and they can also tell if you enjoy being their teacher. I was talking to one of my former students a few weeks ago, who has been out of high school for about seven years. Some of the content we covered many years ago was not so clear in her mind, but she did remember the relationship we developed. She told me what made me special as her teacher was how I made her feel. She shared with me that I was always fair and decent to everyone. Moreover, I was genuinely concerned with each and every student’s success in class and always found a way to motivate them. She remembered a sticky note a laid on her desk the week of Thanksgiving which said, “You are one smart turkey and I am so glad to have you in my chemistry class.” She still has the note today. This is the most rewarding thing I have ever heard; well, other than “I became a teacher because of you.”

I have the gift of making students laugh. I have the gift of making learning fun and relevant. I have the gift of challenging students to love science. I have the gift of compassion, showing students that I care. So even if I have now discovered I cannot change the world in the ways I used to imagine, I do have gifts that allow me to influence the world, one student at a time. I have the gift of being able to do this every single day.

Wednesday, October 13, 2010

Bright and Shiny Pennies

Nothing's nicer than a shiny new penny, but it doesn't take long for those pennies to become old and dull.  However, by following the simple easy steps below, you can make your old pennies shiny and like new again...fast!  You can also learn a little science while you're doing it.

What you need:  A few old pennies; 1/4 cup white vinegar; 1 teaspoon table salt (sodium chloride); a non-metal bowl; paper towels.

What you do:  Combine the salt and vinegar into the bowl and stir well.  Place the pennies in the bowl for approximately 30 seconds. Don't leave them in there too long (or do, and see what happens). Remove the pennies, rinse them with water and dry.  In less than a minute, you've gone from old dull penny to new shiny penny...now where's that gumball machine?

How does it work?  Pennies are made from the metal copper.  Over time, the copper reacts oxygen in the air to form a chemical compound called copper oxide on the face of the penny.  Copper oxide gives old pennies that dull, greenish color.  Vinegar is an acid which reacts with copper oxide, causing it to dissolve away from the penny.  The salt increases the solubility of copper oxide, which means it allows more copper oxide to dissolve in the vinegar solution.  If the pennies are left for too long, a light blue-green color will form on their surface.  This compound is called malachite, and it is caused by the reaction between copper, oxygen, and vinegar.  So, just the right amount of time in the vinegar will give you that shiny penny you desire.

This is a great activity for pre-K up to 5th grade students.  The chemical change at the surface of the penny is striking, and it happens so quickly that it is impressive.  Put some pennies in water for a comparison experiment that doesn't do anything.  Leave another set of pennies in a vinegar solution for longer to see the formation of malachite.  Thanks to Patricia Wong of U.T. Arlington for contributing this activity to DISCUS.  Patricia cites a chemistry blog by Anne Marie Helmenstine on about.com for inspiration for this activity.  That blog entry can be found here.

Egg in a Bottle

Want your friends to think your a genius?  Tell them you can make a hard-boiled egg squeeze through the opening of a Gatorade bottle in one piece, without touching it.  Then, follow the steps below.

What you need: a hard-boiled egg, deshelled; an empty Gatorade bottle; a strip of paper (~3 inches x 3 inches, rolled up); a match or lighter.

What to do:  Light the paper with the match or lighter and drop it into the Gatorade bottle.  Quickly take the egg and place it over the opening.  Watch as the egg is sucked into the bottle, all on its own.

How does it work?  Before you start, the pressure on the inside of the bottle and the outside of the bottle are the same.  When you drop the lit paper into the bottle, you heat the surrounding air, causing it to expand.  When you place the egg on the top of the bottle, the fire inside the bottle quickly uses up all of the oxygen and goes out.  At that point, the air in the bottle cools and contracts.  When this happens, the pressure outside the bottle is greater than the pressure inside the bottle.  This difference in pressure causes the egg to squeeze through the opening into the bottle.  Magic? No... Science!

BE CAREFUL performing this activity at home - it requires fire.  We recommend this activity for high schoolers and also recommend adult supervision.  Instead of a plastic Gatorade bottle, an old glass milk bottle is a great alternative.  Always use care when performing experiments that require open flame.  Thanks to Krishna Pabba of U.T. Arlington for contributing this demonstration to DISCUS.  Krishna credits information he obtained from a University of Wisconsin website for this activity.  It can be found here.  Also, another U.T. Arlington student, Patricia Wong, performed this activity and took a nice video, which can be found here.  Thanks Patricia.

Tuesday, October 12, 2010

Look Ma! No hands! (Deshell an Egg with Vinegar)

 I know.  I hate it too.  You try to peel that hard-boiled egg and it takes forever, it's messy, and you lose some of the good stuff with the shell.  Well, try this instead.  It takes a little longer (OK, a lot longer...about 2 days), but it's still pretty neat.

What you need:  2 hard-boiled eggs; 2 short glasses; white vinegar; water.

What to do:  Fill one glass with vinegar and one glass with water.  Leave enough room in each so that you can put one hard-boiled egg in each and no liquid overflows
after 6 hours
(hmmm...what volume of liquid will a boiled egg displace?...perform the experiment is a measuring cup to find out).  Next, wait...for a good long while...come back in 6 hours to check it, and you'll see bubbles forming.  Wait up to 48 hours and you'll see the finished product.  Carefully pour the liquids off from the eggs and rinse the eggs with water.  The shell of the one which soaked in vinegar is completely gone!

What happened?  97% of the eggshell consists of a salt called calcium carbonate.  As you might guess, calcium carbonate does not dissolve in water alone.  If it did, you would never be able to boil the egg in the first place.  However, vinegar is actually a 5% solution of acetic acid in water (you can use your cabbage juice indicators to check the pH).  Calcium carbonate is soluble in an acidic solution. When the shell starts to dissolve, the calcium carbonate is converted into calcium salt, carbon dioxide, and water.  The carbon dioxide creates the bubbles around the egg.  When the shell finally dissolves, the egg floats (it is less dense than the solution).

Basically anyone can do this activity, as long as they have a little patience.  To understand some of the concepts of acids and bases, we recommend this activity for 6th - 8th grade students. Thanks to Nam Tran of U.T. Arlington for contributing this activity.  Nam credits the great lesson he obtained from the "Science Junction" home experiments website hosted by N.C. State University (there are a couple of other activities there, which we will cover later, too).  Tell us what you think.  (You can even eat it afterward...we didn't, but tell us how it tastes)

Dancing Raisins

There was a classic commercial several years ago with cartoon raisins in sunglasses singing, "I Heard it Through the Grapevine," but this is a little different.  This activity is still entertaining, even if it might be difficult to outfit your raisins with little sunglasses.

What you need:  A tall, clear glass or cup; 1 can of club soda, sprite, or seltzer water (can't be flat); raisins.  Really, that's all.

What to do:  Pour the soda in the glass and drop a few raisins in.  Watch the raisins go up and down for up to 5 minutes!

How does this work?  Initially, the raisins sink, but then as bubbles from the carbon dioxide in the soda form on their surface, it causes them to rise again.  Soda contains dissolves carbon dioxide (CO2), which slowly bubbles out of solution over time.  These bubbles attach to the raisins and eventually provide enough lift to carry them to the top of the glass.  When the raisins reach the top, the bubbles burst and the carbon dioxide is released into the air above the liquid. The raisin then sinks and the process repeats itself.  Simple, but cool.

This is one of those actitivies that is better observed in video, than in pictures.  To see a short video of the dancing raisins, click here.  Thanks to Patricia Wong from U.T. Arlington for contributing this activity to DISCUS.  It is safe and simple...great for elementary school children or even pre-K.  When the students look close enough they can even see the bubbles forming on the raisins that causes them to rise to the top.  Ask them what they think is happening (Try it with chocolate chips, too).  Patricia cites Mary Elizabeth off of pbskids.org for this activity, a URL for which can be found here. As always, we would love to hear your comments about this activity.  Did it work?  How can you make it even better?

Monday, October 11, 2010

Secret Message Revealed

Secret messages and codes are as old as writing itself.  However, the best secret messages are written in invisible ink.  Follow the activity below to learn how to write and then reveal your own secret messages.  This is a great activity for 4th - 6th grade students.

What you'll need:  Medium-sized bowl; Tincture of iodine (this can be purchased at any drug store); Q-tip or small brush; lemon; notebook paper; and cup.

What to do:  Squeeze the lemon into the cup.  Using the Q-tip or the brush, write your secret message on the paper, and then let the paper dry.  While the paper is drying, add 0.5 cup of water to the bowl and 10 drops of iodine.  Stir the mixture well.  When the paper is dry, you can dip it into the bowl.  Voila! Your secret message is revealed.  The paper will turn a dark purplish color, except where you wrote your message.

How does it work?  The color change is due to a chemical reaction between the paper and the iodine.  Paper is made of starch.  When the iodine binds to starch, it makes the dark purple color, which is visible to the eye.  Lemon juice contains vitamin C.  When you write on the paper with lemon juice, you saturate part of the paper with vitamin C.  When iodine binds with vitamin C, it is colorless.  This difference in absorption and reflection of light (dark purple vs. clear) in the different areas of the paper reveals your message.

Thanks to Sabra Ramirez of U.T. Arlington for preparing and presenting this activity for DISCUS.  Sabra obtained information about how to do this activity from Janice VanCleave's "Chemistry for Every Kid:  101 Easy Experiments that Really Work," published by John Wiley & Son's, Inc.  We hope you enjoy this activity, as well as try many of the other activities we have posted in our Activity Corner. If you have your own suggestions for neat at-home activities, let us know about them.

Sunday, October 10, 2010

Colored Foamy Fountain (Elephant Toothpaste)

Want to make bursting colorful foam? Here is how you do it, using only materials you can find at home. It is easy and fun, and it's called Elephant Toothpaste.

You'll need these materials: Safety goggles; 16 oz. empty plastic bottle; 0.5 cup of hydrogen peroxide (6% or "20-volume" is good and can be obtained at a pharmacy or salon); 1 tbsp. dry yeast; 3 tbsp. warm water; 1 tbsp. dishwashing soap; 8 drops of food coloring (be creative with colors!); a small cup for mixing water and yeast; a small funnel.

Get prepared: Use safety googles to protect your eyes. Make sure to do the experiment on a surface or in a tray that can be easily cleaned. You are going to make a lot of foam!

Here's what you do: Use the funnel to add 0.5 cup of hydrogen peroxide into the empty bottle. Next, add 1 tbsp. of dishwashing detergent and 8 drops of food coloring (any colors). Swirl to mix. In a separate cup, mix thoroughly 3 tbsp. of warm water with 1 tbsp. of yeast. When you are ready, use the funnel to quickly add the yeast solution to the hydrogen peroxide solution. Stand back and watch!

What's happening? Hydrogen peroxide is H2O2, which means it is water (H2O) with one extra oxygen. When yeast is added, it acts as a catalyst to split the hydrogen peroxide into water and oxygen. Bubbles of oxygen are trapped in the soap, which transforms into the foam fountain we observe. This experiment is an exothermic reaction; it releases heat. The bottle is warm to the touch after the experiment is over.

This is a great high school level at-home experiment, but remember, it is messy! Thanks to Nour Hussein of U.T. Arlington for submitting this to DISCUS. She acknowledged http://www.sciencebob.com/ and http://www.youtube.com/ for information on how to set up and perform this great activity.




Wednesday, October 6, 2010

Homemade Lava Lamp, Part 1 - Your First Try

There are many ways to make homemade lava lamps.  If you surf around the web, you can find directions that vary a great degree in complexity.  Here we give you the simplest (and cheapest) approach to making one of your own.  It's a great lesson in density, but depending on how far you take it, can also include lessons on solubility and colors.

First, find an empty 1-L or 2-L plastic bottle.  Fill the bottle between 3/4 - 4/5 of the way full with water.  Next, add a few drops of food coloring to achieve the desired color for the water layer (try not to make the color too dark or the effects can be hard to see).  Next, fill the bottle the rest of the way full with olive oil.  Finally, add about 1/2 teaspoon of table salt (for a 2-L lava lamp).  You will see quickly, and probably expect, that the oil and water do not mix.  The oil floats on top of the water, because it is less dense.  The salt will push some of the oil to the bottom, and will create some motion to your lava.  It also facilitates the formation of lava bubbles. As the salt dissolves in the water, it will allow the oil ("lava") to rise again to the top.  You can add more salt to create the effect again.  You should be able to add a lot of salt until no more dissolves in the water.  

The salt can be used to make the oil move up and down, but over the long term, you are not going to want to have add salt everytime you want to make the lava move.  As an alternative, you can slowly turn the bottle over to see some neat rivulets of lava formed along the wall of the bottle, as the oil moves back to the top of the mixture.  This can be done over and over and makes a neat effect.  Make sure that the bottle is capped securely before turning, tipping, or shaking the bottle.

This is definitely an easy and inexpensive lava lamp to create.  This is one of the demos we featured at our Texas State Fair booth - simple, but effective.  No heat lamps or electricity needed - just oil, water, food coloring, salt, and a little tipping/turning of the bottle.  Hope you enjoy.  Thank you to Erin Maxfield of U.T. Arlington for contributing this activity.  We'll present some more complicated versions of the homemade lava lamp soon.

Tuesday, October 5, 2010

YouTube of DISCUS at the Texas State Fair

U.T. Arlington's University Communications produced a great piece about DISCUS at the 2010 Texas State Fair.  In this 45 second video, which is available through YouTube, DISCUS Director Kevin Schug explains some of the important components of the program.  To view the video, click here.

CBS 11 News Coverage of DISCUS at the 2010 Texas State Fair

Some nice coverage of the DISCUS program at the 2010 Texas State Fair was aired by CBS 11 News on Monday, October 4th, 2010. In "Through the Lens" by Mike Kinney, demonstrations of fun science activities were highlighted, including an overview of the program.  DISCUS Director, Dr. Kevin Schug, and U.T. Arlington graduate student Sam Yang were featured in the piece.  You used to be able to view a video of this report, but that has been unfortunately removed from the archive site.

Sally Ride Science Festival at U.T. Arlington, Oct. 30th

The DISCUS program will be featured prominently in the street fair at the Sally Ride Science Festival on the U.T. Arlington campus on October 30, 2010.  A wide variety of exhibits and workshops will help encourage greater interest in science and math for girls in grades 5 - 8. Astronaut Barbara Morgan will be a featured speaker at the festival.