Severe Weather- Lightning and Thunder-Not So Frightening Lightning

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Objective

Students will conduct an experiment to create an electrical charge.

Big Idea

Where does lightning come from?

Hook

10 minutes

I rang my chime to get the class’s attention.  I announced that we were about to begin the first Science lesson in our unit about severe weather.  I asked them to return to the carpet squares and ‘Show Five’.  Once they're seated, I begin with a question.  I like to do this both as a pre-assessment and create immediate engagement by using them as a resource.  “How many of you have seen a cloud?”  “Me!”  “Do clouds always look the same?”  “Yes”  “No way!”  ”No, they’re different shapes.”  Now I asked the class to make their arms and hands into a circle over their heads.  “Pretend you are a cloud.  Now look around you.  Is there more than one kind of cloud in the room?”  “Yes”  “So you discovered clouds can be unique..different.  We’re going to learn how some clouds can indicate weather and be another form of data that meteorologists use to predict weather.”  I give them 2-3 minutes to explore this idea before I get their attention with the ring of our chime.

Always careful to use Science vocabulary, I say, “I need a Science Assistant to help me with a demonstration of this concept.”  I wanted to get a very engaging visual to begin this lesson so I show them the classic ‘Rub The Balloon of the Hair and Watch It Stand Up” trick.  I blow up a balloon and explain, “With the air in this balloon, I’m demonstrating air pressure.  Remember that from our Weather Unit?”  “Kind of…”  “That’s OK, we’ll show it to you again now.  Look how I increase the air pressure in the balloon to make it bigger.  Now, I’ll rub the balloon on his head.  What’s happening to the hair?”  “It’s straight up!”  “That’s a sign that the positive charges are attracted to the negative charges.  That shows that static electricity is present.”  To keep this lesson moving, I don’t go too much into instruction here, knowing that there’s plenty coming up.  “Let’s show our Helper some appreciation!”, as we clap

 

Whole Group Instruction

15 minutes

I make a quick transition back to the subject of cloudsI like to keep the students engaged, so I often ask questions and leave the ends of my sentences off so they can fill them in.  “When storms begin, the first sign is often a cloud..or a group of them.  Cumulus are the big, puffy, white clouds that you often see.”  “I make shapes out of them!”  “That’s a fun way to observe different clouds and to see their differences.  Another difference is the color.  When a cloud is puffy and gray..sometimes really dark grey.., it indicates- that means shows- the presence of a storm.  Those are called cumulonimbus clouds.  Can you say that with me?”  I like to have student repeat important vocabulary words because research supports that this type to active practice will help them better retain new concepts.  I repeat it very slowly, “Cum..u..lon..im..bus.  Who has seen clouds like this?”  “Me…”  “The most interesting thing I learned about these clouds is that they contain electricity, like a….”  “Battery!”  “Exactly like a battery!  When a storm is present, the clouds make an electricity sandwich.  Do this with me (as I demonstrate it with my hands) “Positive-negative-positive”.  I go on to explain, “Electrical currents happen when a positive current comes up against a negative current.  And when the currents are reeeeeeeally big, it creates a really big…CLAP!  Lightning results!”.  Even if I wanted to stop them (which I didn’t!), random claps echo in the class.  I gave them an opportunity to use movement to enjoy and explore this idea for a few seconds before I stopped them with the chime and continued. 

“Thunder is something closely related to lightning.  You’ll always hear thunder after you see lightning.  Anyone know why?”  “Because it’s a piece of the sandwich?”  “Well..it’s more like a result of the sandwich.  Thunder is actually caused by the lightning.  As the charge creates the lightning, it heats up the air around it.  So when a bolt of lightning heats this air along its path, that air quickly expands.  Thunder is the sound caused by that rapidly expanding air.  If the charge is big, it creates a big…."  “Big thunder!”  “Right, it creates a big thunder clap.  If it’s small, it creates..?”  “A small clap?”  “We probably wouldn’t even hear it.  The bigger the charge and the closer it is, the bigger the sound.  Since light travels about five seconds per mile, you can count from the time you see the lightning to know its distance from you.”

I felt that the instruction part was over and I wanted to move on to a demonstration that would help the students visualize the lesson.  “Since lightning forms the basis of this lesson, who wants to help with an experiment?”  Knowing full well the answer, I wasn’t disappointed when I heard many students answer “Me!” 

Small Group Instruction

10 minutes

Materials:

• Foam plates/trays (if the store doesn't have them, ask a friendly meat department!)

• New #2 pencils with erasers

• Flat thumbtacks 

• Wool pieces, small (~2" square)


Because it is a formative assessment, I wanted to make the instruction of the upcoming experiment precise.  “Have any of you ever stood on a carpet, touched another person, and created a pop, a charge?”  When nobody raised their hand, I continued, “You may have felt this and not even known what it was all about.  It happens a lot when the weather is stormy.  These ‘pops’ are something called ‘static electricity’.  Since all electricity is basically the same, we’re going to create some so you can see how the positive and negative charges come together to create lightning.

To create lightning, we need to create some electricity.  I have two plates, one foam and one aluminum, like a pie plate.  I also have a new pencil, a flat thumb tack, and a small piece of wool.  Wool is good to use because it’s a natural material from an animal and transmits the charge kind of like we did with the hair experiment.”  I found a great example of this experiment.  The website itself is one of the best I’ve seen to illustrate weather related concepts to young students.  To make it easier, we found that a foam tray cut up into smaller sections worked very well (because funny enough, foam plates aren't easy to find anymore!).

• First, we’re going to use the tack to stick the pencil to the pie plate so it can act as a kind of handle so we can twirl it around.  

• Next, we need to use the wool and other plate to create a base to rub against.  So we’ll turn the other plate upside down and put the fabric on top of it. 

• Then, take the pencil in our hands and roll it back and forth as fast as we can. 

"This movement creates friction, which pulls the positive charges together, which creates heat, which- in a cloud- creates..”  “Lightning”  “Yep, and if we do it right (because we experiments don’t always work right the first..or even seventh time) we can create the same effect as lighting with the negative charge in our hand are attracted to the positive charges in the plate.”

After I use a chime dismiss them back to their tables, I have them begin the experiment.  To make for easier logistics, I have already sorted the materials and placed them on the tables.  I have a helper in the class (since I don’t often have this luxury, I plan my more detailed activities for the times when I know I will have help) and we both circulate around to help the students construct the ‘lightning plates’.  As the students begin to build the structure and begin the experiment, I gave them them important reminder not to touch either plate during the experiment to avoid grounding the charge (yes, that was another new word, though for the sake of time and attention span, I did not get into the definition). As I move around the room, I listen for comments that show they recognize the Science phenomena they observe.  While the lesson is fairly packed with new concepts and vocabulary, the experiment is fairly simple.  In order to let all of the students at the table get a chance to be ‘shocked’ by the lightning, I let them continue with repeated experiments for the next several minutes.  Some work better than others, necessitating some good old fashioned perseverance, a good Science lesson in itself.

Wrap Up

5 minutes

Once the activity had wound down, I rang the chime and asked the students to return to their carpet squares as the helper and I quickly picked up the materials.  I asked them what they learned about lightning that they didn’t know before the experiment.  “I learned that positive and negative charges make lightning!”  “I learned that opposite things can make a lightning spark.”  Answers like this are appropriate for this age and set a good ‘positive’ foundation to better understand electricity.