Severe Weather - Blizzards - Let It Snow!

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Objective

Students will explain how snowflakes are formed to cause blizzards by sketching different crystals.

Big Idea

Why is it important to know about snowflakes?

Hook

5 minutes

I ring my chime to get the class’s attention.  I announce that we were about to begin the fifth Science lesson in our unit about severe weather.  I ask them to return to the carpet squares and ‘Show Five’.

Since the movie, 'Frozen', is still so fresh in the minds of my students, I decide to use a song from the soundtrack as a hook.  Without telling them, I cue up the song, “Let it Snow”.  Just as I expected, within a few notes, the students perk up ("Even the boys!”, my daughter said) and begin to sing along.  As soon as the song ends, I ask them, “What kind of weather do you think we will learn about now?”.  “Snow!!!”

Whole Group Instruction

15 minutes

As I hold up a satellite picture of a blizzard, I ask them "Does this remind you of anything?  If you have an idea, put your thumbs up.  Stay quiet so everyone's idea are respected."  I begin the instruction, “Who has an idea to share?”  “A hurricane!”  Since we had recently completed a lesson on that, I took this opportunity to connect to prior knowledge.  “In ‘Frozen’, Anna and Elsa got caught in a huuuuuge snowstorm.  When these storms have sudden, very strong winds, they’re called ‘blizzards’.”  As I give this instruction, I demonstrate this with my hands.  My nature is to ‘talk with my hands’ anyway.  With material like this, it adds a nice visual element.  “Say that new word..’bliz-zards’”. “Bliz-zards”  I usually have students repeat new vocabulary words to give it better context and retention. 

I take a minute to introduce the book Whiteout by Rick Thomas.  I like this book because it gives specific information, both about the elements of a blizzard and the effects on the community.  “As a blizzard forms, precipitation- rain- becomes snow and gets caught in a powerful stream of cold air pushing in different directions, top and bottom, until it starts to freeze. This frozen precipitation gets caught in a powerful wind force, where it's hard to see.  The snow gets heavy and blows large amounts on the ground, building up huge mounds and layers."  As I share this information, I pass around two pictures that show how much snow can fall in a short time.  "Look at these two pictures.  In one, you can see how one storm practically buries the telephone pole.  In the other, you can see how the snow is almost at the level of the cars in the street.  Blizzards can have some really big effects to their communities.      

“If you looked really close, like under a microscope, you'd see that snowflakes are really frozen water crystals.”  Since we’ve covered other parts of severe weather in this unit, I decide to break down the elements of a blizzard and focus on the snowflake crystals in an observable way to provide the students with a deeper understanding.  “These snowflakes start as a tiny water droplet, mist.  These droplets attach to particles (like dust or ash) in the air.  As it gets colder, these frozen crystals either keep growing or attach themselves to other crystals.  Pretty soon, more crystals keep.."  "Growing".  Before you know it, you have…..”  “Snow”.  “Right, add in some really strong wind and a lot more snow.  What does that become?”  “A blizzard.”  I often stop sentences to assess the student knowledge by giving them an opportunity to verbally fill in the blanks.  It's always good to take any opportunity to engage! 

 

Small Group Instruction

15 minutes

After the whole class instruction was finished, I tell them “It’s time for us to be scientists and study crystals.  We are going to look at some pictures and see three different kinds of crystals.  Why could it be so important to learn about crystals?  Take a minute to talk about this with your partner.”  I give them minute to discuss this.  I’m looking for answers that talk about either snow, or the formation process of a snowflake..or both.  “If we know how snow starts, we know how bad it will be.”  “Definitely.  The more we know about the weather, the better we can prepare for it.” With this description, I use a chime to dismiss them to their tables, pass out copies of the pictures to each table, and begin the instruction piece

“No crystal- like no snowflake- is the same.  They develop differently depending on the amount of moisture, particles, and time.  We are going to study three different kinds of crystals and record what we observe.”  I choose these specific crystals- Alum, Table Salt, and Epsom Salt- because they are easily accessible and differentiated.  I plan to do an experiment to recreate them in the next lesson and familiarity is important to enhance the context.  “The first thing we need to do is look at the crystals in the pictures.  Next, use a pencil to sketch- lightly draw- what you see.  Remember when we studied animals?  We learned that naturalists like Charles Darwin use sketches to record what they observe, both so they can remember and share what they learn with others.”   When practical, I work to revisit previous lessons to access prior knowledge and help students see alternative applications to common Science skills.  To better organize the data, I prepare a paper and label each column with a different salt- Epsom, Alum, Table.  Since I plan to use this same recording sheet in the next lesson, I label the rows ‘Image’ and ‘Actual’.  I pass out one of these sheets to every student.  “Take turns with the magnifying gasses so you can look very closely at the crystals.  It won’t take long so be sure to discuss your observations with the others at your tables while you are waitingAs soon as you notice something, record it on the paper.”  After everyone has had a turn to view and record all three images, I ring the chime and ask the students bring their papers to their carpet squares to use as reference for the next step.  

 

Wrap Up

5 minutes

We sit back on our carpet squares.  I ask them to use their papers for reference.  I use a quick chart that I labeled with a column for each salt.  “What did we notice with the alum crystal?”  “It’s big like a block.”  “So I’ll write ‘block’ under Alum.  What about Table Salt?”  “It’s in smaller pieces.”  “So I’ll write ‘smaller’ under Table Salt.  What about Epsom Salts?”  “It’s pointier.”  “So I’ll write ‘long and pointy’ under Epsom.”  Once these quick references are collected, I collect the papers to save for the next lesson and end the lesson.