Bacteria: When Do You Make Me Sick?

Has this ever happened to you....

You wake up and head to school feeling fine.  By lunch you're starting to feel icky and by the end of school you're sick. 

Under the right circumstances, bacteria can reproduce every 20 minutes. 

Have your students determine how many bacteria will exist after 10 hours, if they begin with just one.  They'll have to do their calculations in their head/on paper, as a calculator will quickly become useless!

Scientists believe that humans can start to feel the effect of harmful bacteria when there are about 2000 bacteria in the body.  How many minutes/hours did it take to reach this number? 



If time permits and you're willing, you could use popcorn kernals to model the number of bacteria (up to a certain point....).  Have your students count out lots of 10 kernals in small cups - it makes it easier to count out 100, etc.

Volcanoes: Make a Model

You can find all sorts of volcano making/exploding kits to buy.  (If you're interested in buying, each of those words is a link to a different product).

But you can save your money and have a little more (messy) fun by making your own.

Start with an empty bottle - a Snapple bottle or soda bottle works well.  Tape it to a paper plate - makes it sturdier and easier to work with.

Mix up some paper mache.  There are all kinds of recipes out there.  I'm partial to just flour and water - cheap, easy to procure, and easy to clean up.

Dip strips of torn up newspaper in the paper mache and start applying them to the bottle.  Build up the shape of the volcano as you wish.  Make sure you keep the top of the bottle open!

By making your own model, you have the chance to make it the shape you want... make it a shield volcano, a cinder cone volcano, a composite volcano.  Even if you don't have a sepcific plan, it gives you a chance to review and discuss those types of volcanoes and how they're formed.

A cinder cone volcano

Allow your volcano to dry - the amount of time this takes depends on the weather and how heavy-handed you were with the paper mache.

Once the volcano is dry, you can choose to paint it. 

Or you can just get on with the exploding part.

Put some baking soda in the bttle.  You can add some red food coloring, for effect, if you wish.  Pour in some vinegar and stand back and watch!

And, if you're too impatient to build the volcano and just want to get to the exploding part, you can just put some baking soda in an empty bottle, add some vinegar and watch.  It's a good demonstration of a chemical change, even if you aren't studying volcanoes!

Cartesian Diver

Cartesian divers  are used to demonstrate the effects of air pressure. 

I used an eye dropper filled part way with water for my diver.  I put colored water in the eye dropper - I think it makes it easier to see what's happening.

Fill a large, plastic bottle with water.  Place the diver in the bottle - the diver should float at this point, make any adjustments you need to to make sure that happens.

Put the cap on the bottle.

Squeeze the bottle and watch the diver dive! 

Why does it dive?

When you squeeze the bottle, you compress the air molecules that are trapped in the bottle, including those inside the eye dropper.  When that air is compressed, additional water enters the dropper (since there's room available).  The additional water (and decreased volume of air) changes the density of the dropper enough to cause the dropper to sink to the bottome of the bottle.

When you release the sides of the bottle, the air trapped in the dropper expands, pushing out the extra water and decreasing the density so the dropper rises. 

A Cartesian diver can be used to explain all kinds of things, like how submarines work, how fish swim bladders work, etc.
******
You can also use ketchup (or other condiment) packs as Cartesian divers.  In that case, water doesn't enter the packet, it dives strictly because of the change in density due to the compression of air molecules.

Books: A Short History of Nearly Everything

I've drawn attention to A Short History of Nearly Everything, by Bill Bryson before (not on this blog, but elsewhere).  I LOVE this book.  I find it utterly fascinating and fun to read.  It is Bill Bryson's attempt to understand the oldest questions posed about our universe and ourselves. In his words, "The idea was to see if it isn't possible to understand and appreciate - marvel at, enjoy even - the wonder and accomplishments of science at a level that isn't too technical or demanding, but isn't entirely superficial either."

In my opinion, he succeeded!

If you read it, you'll be amazed by how much we know about the world around us, and stymied by the vast amount of information that remains unknown. 

I am particularly fond of the analogies Bryson uses - I find that they make the material accessible as well as just plain fascinating.  He covers some pretty heavy topics, but the way he writes makes them understandable (and interesting) to even middle school students. 

Here are a few examples.

First, on how small a proton is...

 A proton is an infinitesimal part of an atom, which is itself of course an insubstantial thing. Protons are so small that a little dib of ink like the dot on this i can hold something in the region of 500,000,000,000 of them, rather more than the number of seconds contained in half a million years.

And then, on how large space is....

Our nearest neighbor in the cosmos, Proxima Centauri, which is part of the three-star cluster known as Alpha Centauri, is 4.3 light-years away, a sissy skip in galactic terms, but that is still a hundred million times farther than a trip to the Moon. To reach it by spaceship would take at least twenty-five thousand years, and even if you made the trip you still wouldn't be anywhere except at a lonely clutch of stars in the middle of a vast nowhere.

And, finally, on how little we even know about our own home....

The distance from the surface of the Earth to the center is 3,959 miles, which isn't so very far.  It has been calculated that if you sunk a well to the center and dropped a brick into it, it would take only fourty-five minutes for it to hit the bottom (though at that point it would be weightless since all the Earth's gravity would be above and around it rather than beneath it).  Our own attempts to penetrate toward the middle have been modest indeed.  One or two South African gold mines reach to a depth of two miles, but most mines on Earth go no more than about a quarter of a mile beneath the surface.  If the planet were an apple, we wouldn't yet have broken through the skin.  Indeed, we haven't even come close.

One of the other great things about this book is that you can pick it up, flip it open to a random page (or chapter) and start reading, as I did several times in looking for the above quotes. 

Get yourself a copy of A Short History of Nearly Everything - you can most likely get it at or through your local library.  Although, you might want to get your own copy so you can mark it up with your own notes, exclamation points, and underlining (although I gave up on all that when I found that I had underlined or bracketed almost every paragraph in the first two chapters).

Chemical Changes: Clean Your Silver

Line a non-metal container with aluminum foil.

Place tarnished silver in – make sure it touches the aluminum foil.

Boil water and add baking soda (1T per cup of water).

Pour this solution over the silver.

You'll quickly discover some shiny silver and may see a yellow haze on the aluminum foil.

I didn't fully submerge the lid, so you can see some of the tarnish at the top, and the "polished" part at the bottom.  It's not the best photograph, but it is nice and shiny (so much so that it reflects all kinds of other stuff and ruins my picture). 

Why:

The tarnish is silver sulfide, which forms from a reaction with sulfur in the air.   Sulfur has a greater affinity for aluminum than it does for silver.  So when you place the tarnished silver in the baking soda solution, the solution carries the sulfur to the aluminum.  The yellow haze on the foil is the sulfur that has been deposited there. 

The chemical equation:
Silver sulfide + Aluminum --> Silver + Aluminum Sulfide

Some Side Notes:
After hearing about this demonstration numerous times, I decided to give it a try (and get some pictures so I could share it with you).  It worked so well!  The yellow that's left on the foil isn't real apparent, although you could see an outline from where things had been sitting.  But, what was very apparent was the smell of sulfur, as soon as the solution was poured over the silver.  Wow!  I wasn't expecting that, but it certainly confirmed that the tarnish was composed of sulfur!  I'm now in search of a large enough vat to use to "polish" the teapot that goes with this lid! 

One more thing.... when researching the exact chemical equation I learned something else.... traditional silver polishes actually remove small amounts of silver along with the tarnish.  This method only removes the tarnish.  Seems like the way to go - no polishing and keeps the silver fully in tact!
*****
Presented at the 2003 New Jersey Science Convention.

Classification: Scavenger Hunt

Provide students with a list of questions, such as:
*What is the common name for Felidae domesticus?
*What is the red squirrel’s order?
*What is the scientific name for the giant panda?

Students use the internet to find the answers to as many as possible.

Turn it into an assignment, a contest, extra credit, etc.

Minerals: From Observation to Definition

On the first day of our mineral unit, I have students spend the period observing 12-15 different minerals.  The minerals are each accompanied by an index card with the mineral's name on it. 

Students must write down 3-5 (depending on the students) observations about each mineral: state of matter, color, shape, shiny-ness, etc.

For homework, I have students use their observations to draft their own definition of what a mineral is.  They're looking for things that all of the minerals they observed have in common.  At the very least, they should get "solid" as part of their definition.

I then have them look up the textbook definition and we proceed from there.

Graphing: Growing Monkey

Look around your favorite retailer for these Growing "Things". I've seen turtles, crocodiles, princesses, pirates, etc.

We happened to have a monkey (thanks Aunt Amy - I told you it would show up on here!).

Take some measurements of your "thing" before you do anything with it.

Then place it in water.

Most of these say they'll take up to 72 hours (that's 3 days) to reach full size. I recommend you start on Monday, so you'll have all week to watch it.

Each day, at the same time (or as close as you can come), retake the same measurements you took initially.

At the end of the week, you should have several data points that can be graphed. Older students could determine the rate of growth.

You may even want to have them look at the data after 24 and 48 hours and ask them to predict how large it will grow by 72 hours.

*****
My apologies, my "after" pictures of your monkey didn't turn out, so I don't have much for you. Our monkey about doubled in size. Some of the "things" out there are a lot smaller to start with and claim to increase by 600%, which should give you some great measurements.

Dress the Part: Mitochondria Scarf

Several years ago, on the day of my 7th graders' cell quiz, one of my students, showed up wearing this beautiful scarf.  Yes, those are drawings of mitochondria!!  Her mom (a biochemist, I believe) had loaned her the scarf for good luck on quiz day.  (It worked - she did well!).

I have since become proud owner of one of the same mitochondria scarves by a Slice of Life.  It's a beautiful silk scarf and so much fun to wear. 

I also have this one:

It's connective tissue, in chiffon. 

And, if you're not into scarves, you might want to check out the ties:

Balancing Equations: Cupcake Chemical Equation

The importance of balancing chemical equations and the idea of limiting reagents can be difficult for young chemists to understand. To help them, provide students with a chemical equation that's more familiar and interesting to them:

1 box of cake mix + 3 eggs + 2 cups of water --> 24 cupcakes

Then follow up with questions:

How many eggs do I need if I have 2 boxes of cake mix?

How many cups of water do I need for 2 boxes of cake mix?

How many cupcakes will I get with 2 boxes of cake mix?

How many cupcakes will I get if I have 2 boxes of cake mix, 6 eggs, and 2 cups of water?

Take the questions as far as you wish...

when you make the move to "real" chemical equations and you see some eyes start to glaze over, remind them of the cupcakes!

Animals: Paper Bag Animals

Thansk to Nancy E.-B. for sharing iwth us this idea with us during the 2007 Maitland Simmons Institute.  I love the way your mind works!

Use paper lunch bags to model the simplest of animals:

Sponge: a plain bag

It has an inside and an outside and it just sits there. 

Cnidarian: a bag with the top cut into fringes

Flatworm: a flat bag, stapled/taped shut, with a straw stuck into it in one spot

One opening, through which both food enters and waste leaves. 

Nematod/Roundworm: a flat bag, stapled/taped shut, with a straw passing through in two spots

Separate spots for food to enter and waste to leave.

Topographic Maps: Constructing a 3D Model

Create a 3D model from a 2D map!

You’ll need:
A simple contour map – 2 copies (you can draw one yourself if you can’t easily find a suitable one)
Fun foam*
Scissors
Glue

Procedure:
1. Set aside one copy of the map to use as a reference.
2. On your “cutting map”, cut along the outer-most contour line. Trace around this piece on a piece of foam. Cut out this piece of foam.

3. On your “cutting map”, cut along the next contour line. Trace around this piece on a piece of foam and cut it out. Use your “reference map” to place it in the appropriate place on the bottom layer. Glue it in place.
4. Continue the process of cutting, tracing, cutting, positioning and glueing until you have completed all the contour lines on your map.

*You could also use corrugated cardboard or styrofoam. Fun foam is great because it’s very easy to cut with regular scissors (not the case with cardboard, you’re likely to need something a bit more powerful).

Air Pressure: Straw Fountain

Fill a cup part way with water.

Hold a straw vertically in the water – make sure it’s not touching the bottom of the cup. (You could probably tape the straw to the cup if you’re having a hard time holding on to all of the parts.)

Using another piece of straw, blow across the top of the straw that’s in the water.

What happens:
Water shoots out of the vertical straw.

Why:
Normally there’s a whole lot of air molecules stacked up on top of the surface of the water. When you blow across the top of the straw, you’re pushing some of those air molecules out of the way. There are still air molecules pushing on the rest of the water, and with the pressure over the straw reduced, the water is pushed up the straw.

Tips:
If you're having a hard time getting the water to shoot out of the straw, try some of these tips - they helped me!

1 - Aim the straw you're blowing through slightly up (see picture above).

2 - Use shorter pieces of straw.

3 - Fill the cup with more water.

4 - Practice - it takes a few times to get the technique down.

Favorite Website: The Sci Files

NASA had a program called the problem-based learning series called the Sci Files.  Apparently, back in the early-to-mid 2000s, there were episodes that were aired on cable access stations and some PBS stations.  You can find some available online as well.

I'll admit that I don't know anything about the episodes.  (Which is no doubt leading you to wonder what I'm doing talking about this).

What I do know is that regardless of whether or not you use the episodes, there are some great activities that accompany (but don't require) the episodes available for you to use with your class.  You can find them in a couple of ways...

...if you go to the episode & guides section, you can print out the complete guide for each Sci File. 

...or you can go to the educator's section of the old(er) website and find individual activities and worksheets. 

Some of the 20+ Sci File titles include:
--The Case of the Wacky Water Cycle
--The Case of the Shaky Quake
--The Case of the Disappearing Dirt
--The Case of the Prize Winning Plants

I printed out complete guides of the Sci Files I was most interested in (and thought I would get the most use out of), because the site hasn't been updated since 2007.  It's still there for now, and maybe it will be forever, but it's something to keep in mind. 

Friction: Phone Book Friction

This one takes some prep work (you might want to find some student “volunteers” to help you out), but it’s a fun one!

You’ll need two phone books – the larger the better.

You need to shuffle the pages of one with the other. I wish I had a brilliant technique to share with you on how to do this, but I don’t. Do what works best for you. It doesn’t need to be perfect, but the more pages you get interspersed, the more effective.

Now that the books have been joined together as one, have two students attempt to play tug-of-war and pull them apart.

Ha! They can’t do it! Too much friction!

No surface is perfection smooth – they all have bumps of ridges to a various extent. Friction occurs when two surfaces rub against each other and those bumps and ridges catch on each other.

Each of the pages of the phone book has two surfaces filled with ridges and bumps. And, if you’ve done a good job shuffling those pages, there are a whole lot of surfaces trying to slide past one another. Whole lot of pages, whole lot of surfaces, whole lot of ridges and bumps, whole lot of friction!

******
Presented by Daryl Taylor at the New Jersey Science Convention.

Fungi: Odes to Fungi

One of the activities included with the textbook I used to use was an Ode to Fungi.  The worksheet provided students with four lines of a poem, and then the students were to continue said poem, including various facts about fungi.

I've been known to use that poem starter, but have found that most of my students are happy to start from scratch.  The starter "locks" students into a rhyming scheme and a lot of students take their poems in a different direction, so the rest of their poem doesn't really make sense in the context of the first four lines. 

You can also read the poem "Mushrooms" by Sylvia Plath - proof that "real" poets write about fungi!  This can be fun to read and discuss with your class, even if you don't have your students write their own. 

After students write their poem, usually for homework (after starting it in class), I have them copy it onto a construction paper mushroom.  We then hang them in the hall for all to see.

Earthquakes: San Francisco Earthquake Accounts

I happened to be teaching about earthquakes in April 2006.  I hadn't given it much thought, but I was watching the Today show on the morning of April 18, and there was a segment on the 100th anniversary of the San Francisco Earthquake and Fire. 

Well, the timing couldn't have been better (well... I could have planned a bit further ahead and been a bit more prepared...) so when I got to school that morning I went searching for something to share with my students to mark the date. 

I came across The Virtual Museum of the City of San Francisco.  There, I found a whole collection of eyewitness accounts as well as lots of other information. 

I printed out a few accounts and shared parts of them with my students that day.  These do tend to be longer narratives, so you won't be able to read several whole accounts, unless your students are much more patient than mine. 

Since this was a plan that was hatched about an hour before school started, I read the accounts and left it at that.  You may want to take it further...

Assign each student a different eyewitness account to read as homework.  Then, have them summarize their story for the rest of the class the next day. 

Perhaps you could have your students write their own account of what it would have been like to survive the San Francisco Earthquake of 1906.  Or maybe you'd like them to research another earthquake and write an account of that experience in the first person.  If you live in a place that experiences earthquakes, you could have your students write of their own experiences.  (Talk to the language arts teacher, maybe it'll work out that your students are working on writing first person narratives or memoirs and you could team up).

You could adapt this exercise to other natural disasters: hurricanes, tornadoes, volcanoes, etc.

Density: A Sweet Demonstration

Before your students arrive, unwrap a Snickers candy bar and a 3 Musketeers candy bar (any size is acceptable).

Have a large, transparent container filled with water set up in the front of the classroom.

Drop the two, seemingly identical, candy bars into the water.

One floats, one sinks.

Why?

Nuts are dense. The Snickers, packed with peanuts, sinks to the bottom, while the nut-less 3 Musketeers floats.

You could test your students’ understanding of density by asking them to predict what would happen with other size 3 Musketeers bars. For example, would a king size candy bar float or sink? Some might think it will sink because it’s bigger, but remember, density is an intrinsic property, it doesn’t depend upon size.

How Does that Work: Is All Plastic the Same?

Go through your recycling and pull out several different plastic containers. Cut up the different types and place each in water.

What happens?

Sorry - the PET disappears in the water, but it's there, on the bottom.

PET plastics (soda bottles, #2) will sink. HDPE plastics (milk jugs, #1) will float.

There are lots of different directions you can go from here:

-What do PET and HDPE stand for?

-What are they each made of?

-Why does milk get packaged in HDPE but soda and water in PET?

-Is the recycling process different for the different types of plastics?

-Is one type of plastic more environmentally sound than another?

I'll admit, I don't entirely understand the differences, but that doesn't stop me from sharing things with my students.  It's a great opportunity for us to learn together. 

Acid/Base Chemistry: pH of Household Substances

Gather a large collection of household substances; cleaning products, health and beauty products, beverages, etc. (See below for a more detailed list).

To perform this experiment in a classroom, place a small amount of each substance into a small beaker. Label the substance, either with a label on the beaker or an index card next to the beaker. Place a stirring rod (or comparable tool) in each beaker.

Students will touch the stirring rod to a piece of pH paper. They will then consult the key that comes with the pH paper to determine the substance's pH (I have laminated several of the keys and try to tape one to the end of each lab table, so there's always one nearby and all students are crowded around one or two small pieces of paper).

By touching the stirring rod to the paper (as opposed to dipping the paper into the substance) students will be able to test 3 or 4 substances on each piece of pH paper.

After testing each substance and recording the pH, students can create a pH scale of household items.

Have your students look for patterns... foods, skin care products, cleaning products, etc.

What are the commonly used numbers on the pH scale? Are there any numbers that weren't used at all?

What results surprised your students?

******
Some substances you might* want your students to test:
ammonia
lemon juice
toilet bowl cleaner
Coke
coffee
liquid soap
rubbing alcohol
shampoo**
orange juice
glass cleaner
lotion**
bleach
Borax**
milk
Simple Green
grapefruit juice
vinegar
cranberry juice
tea (regular and herbal)
aspirin**
tub/tile cleaner
Brasso
7-Up
plant acidifier (MirAcid)**
soap scum remover
Drano**
oven cleaner
saline solution (for contacts)
Rolaids/Tums**

*Always use your best judgement and keep your school's policies in mind.
**Dissolve in water.

Genetics: SpongeBob Genetics

If you haven't visited Science Spot yet, you really do need to get there. 

One of the most popular (at least by my unofficial survey of people I talk to and come in contact with) items found there is the SpongeBob genetics worksheets (scroll about half way down the page).  My students LOVE these, and they provide good practice with phenotypes, genotypes, Punnett Squares, etc.  And, of course, she includes an answer key with each worksheet. 

I just hope SpongeBob remains popular for a long, long time! 

Do yourself a favor and get over to the Science Spot! 

Renewable vs. Non-renewable Resources

You'll need two different types of dried beans/peas/lentils.  Pick two kinds that are distinctly different in appearance.  One type will represent coal, the other wind power. 

Before your class arrives, place about 100 of each bean around the room.  They don't need to be hidden, but they should be spread pretty far and wide.  I always tell the students that they don't need to open any drawers or doors to find the resources, but they may be behind something that's sitting out.

Divide your class into two teams.  One team will be the coal miners.  The other team will be the wind farmers.

Show the students what the "coal" looks like and what the units of "wind power" look like.

Send the teams into the field to look for their appointed resource.  Give them 30 seconds to find as much as they can.  When the 30 seconds are over, they should report back to their team headquarters with any resource they found.  While the teams are counting the resources they gathered, take a lap around the room adding some more of the wind power while you go.  After the counting is finished, have each team record the number of resources they collected on the front board.

Give the teams another 30 seconds to collect as much of their resource as they can.  Again, they'll return to their headquarters and count.  And again, you'll add more wind power to the supply. 

Repeat at least one more time (more if you wish).

At some point during the process, the students will notice you adding wind power.  They'll start to ask questions (especially the coal miners!) - I just shrug my shoulders and say we'll talk about it later.

At the end of the experience, the students will notice that the coal miners collected less coal with every round, while the wind farmers collected about the same amount of wind energy with every round. 

In my experience, this really helps young students (I've used it with 4th graders) get a feel for the difference between renewable and non-renewable resources and leads to some great discussions about the two.  And it's really fun! 

******
This activity is based on something I found online one time.  I can't locate my paper, nor can I find it with a Google search.  If anyone's familiar with the original source, please let me know and I'll credit them properly.  I believe it came from an energy company.