How To Teach Science During Dinner… With Salad Dressing

April 15, 2010
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Last we, we explored just a little bit about the science behind salads.  We specifically looked at how to bring leaf lettuce back from the dead (almost).  Don’t think for one minute that we are done looking at vegetables and salads.  We’re NOT!

This week, we have to add something to our salad.  Something that ALL of us use in one form or another (unless you are a rabbit!)  That’s right.  This week we are going to look at…

Salad Dressing!

The four main concepts of science we explore each week can easily be observed with our favorite saucy topping so let’s review them a bit:

Excellent.  Now we can get down to business…

The easiest and most common salad dressing is known as a VINAIGRETTE which is a fancy word for “a mixture of oil and vinegar.”  All you need to do to make vinaigrette is add three parts oil to one part vinegar (i.e. 300mL of Olive Oil and 100mL of Vinegar), the herbs and spices you prefer, and gently shake the mixture before pouring it on your salad.  But how do you get such a great flavor from a mixture of these items?

THE SECRET IS IN THE ATOMS

Scientists call a vinaigrette an EMULSION which means that the ATOMS within the oil and vinegar do not rearrange themselves when they are mixed together.  They hold on to each other!

Any salad dressing that is an EMULSION can easily be found in any salad dressing aisle of your local grocery store.  They are really easy to find!  All you have to look for are the containers with two layers of liquids just resting in place.

HOW DARE YOU CALL MY SALAD DRESSING “DENSE!”

Many people would incorrectly say that the top layer (the oil) rests on top of the bottom layer (the vinegar and spices) because the oil is lighter than the vinegar.

This is not true!

As I explained  in my Classic Science:  Chemistry curriculum, the layers you find in this tasty salad dressing take place because of a difference in DENSITY!  Remember, DENSITY is the amount of ATOMS found within a certain amount of an object.  So, if you were to measure out one cup of oil and one cup of vinegar, you would find that the total number of atoms within the cup of oil would be smaller than in the vinegar.  To put it simply…

Oil is less DENSE than vinegar so the oil floats on top.

VINAIGRETTE IS VERY SNEAKY

If you have ever placed any kind of oil in  your hands like lotion, cooking oil, motor oil, you probably figured out how quickly this stuff spreads all over your hands.  Even if you scrub really hard, you STILL can feel some of that oily mixture on you!  This stuff gets everywhere!

Another way to say this is…

The molecules of oil DIFFUSE very easily onto dry surfaces.

Although this may be nuisance if oil gets on your hands, it is a VERY good property of vinaigrettes.

Since the oil in vinaigrette DIFFUSES very well, it clings to vegetables like lettuce very easily.  And when the vinegar and spices are mixed in with the oil after a good shaking, the flavorful vinegar DIFFUSES around your salad too!

Just remember to keep your salad dry before adding the vinaigrette.  The oil will not be able to DIFFUSE onto the salad if the vegetables are covered in water!

THE MYSTERIOUS LAW INSIDE YOUR SALAD DRESSING

Shaking up an EMULSION doesn’t change any of the ATOMS at all.  You already know that ATOMS cannot be created or destroyed, only rearranged.

However, it does not mean that the atoms HAVE to rearrange!

So go ahead and shake that bottle of Italian dressing as hard as you like.  It may look like you’ve created a whole new chemical, but you are only mixing up an EMULSION.

Learn more about emulsions and other chemistry concepts in Classic Science: Chemistry for the Family and be certain to come back every Thursday or subscribe to The Blog of Mr.Q to learn more about how to teach science with cheap, everyday items!


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How To Teach Science During Dinner… With Salad

April 8, 2010
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I’ve spent many years asking for a side of fries with my meal.  Unfortunately, I’ve reached an age where (perhaps) that is not the best idea all of the time.  Don’t get me wrong!  I love the salty crunch of a deep-fried potato.

However, the more I look at my eating habits over the past few  years, the more I realize how often I turn to our green friends for dinner.

And so, this week, I want to pay homage to…

The Salad!

There is a lot of science going on inside a fresh salad – fruits, stems, roots, leaves…

I COULD GO ON ABOUT THIS ALL DAY LONG!

But I believe we will focus on one little trick that has been known for centuries about salads; namely, how to keep lettuce fresh and crisp.  To do this, we need to review the four main concepts about science in the kitchen:

I’m willing to guess that most of you have seen what happens to the lettuce or any of the vegetables in a salad when it has “gone bad.”  The lettuce wilts as it loses its crispy texture and turns into a gooey mess.

I don’t know about you, but I like the crispy feeling of lettuce when I take a bite.

So how do you keep lettuce crispy?  Easy!  Just put the lettuce in some water and wait for it to firm up again!  How does that happen?

BRING ON THE ATOMS…

The “crispy” feeling of fresh lettuce is really a high DENSITY of water molecules inside the plant cells.  Remember, a molecule of water is a group of three ATOMS (two hydrogen atoms and one oxygen atom).

When these cells have a high DENSITY of water, they are very full of water molecules which make the lettuce feel crispy when you break it apart.

However, large amounts of molecules (like water) tend to move to areas where there are fewer molecules.  This DIFFUSION of water molecules takes place as your salad sits in the bowl for a few hours.  The water moves out of the plant cells and causes the entire lettuce leaf to become limp and soggy.

If you place your wilted lettuce leaf into a glass of water, you will notice after awhile that it will start to get firm again.  But how does the water get back into the lettuce?

DIFFUSION TO THE RESCUE

Since there are more molecules of water in the glass than in the cells of the plant, the water DIFFUSES back into the plant cells.

EUREKA!  YOU HAVE BROUGHT LETTUCE BACK FROM THE DEAD!

(Okay.  It wasn’t really dead.  Please don’t worry about hoards of zombie salads running through your town…)

Of course, you cannot do this trick too many times OR with lettuce that is too wilty.  Just be certain to keep the lettuce nice and cold while you keep in under water.   Heat tends to do bad things to plant cells (and everything else for that matter.)

A SIMPLE LAW FOR YOUR SALAD

What does heat have to do with your wilted salad?  Well, the ATOMS within your lettuce are moving around a lot more as they heat up in that bowl of salad.  They are not being destroyed though.  This is because the LAW OF CONSERVATION states that atoms cannot be created or destroyed, only moved around.  And if you remember, it is the DIFFUSION of water molecules out of the cells that started this whole problem to begin with!

BESIDES THIS TRICK, WHAT IS THE BEST WAY TO KEEP YOUR SALADS CRISPY?

Eat all your vegetables as soon as you can! (You’re welcome Mom!)

Check out the Classic Science:  Physical Science and Chemistry curriculum to learn more about ATOMS, DENSITY, DIFFUSION, and the LAW OF CONSERVATION!

Also be certain to subscribe to Mr.Q’s blog every Thursday to learn more about how to teach science with cheap, everyday items!


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How To Teach Science During Dinner…With Pizza (Part II)

April 1, 2010
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This week we are going to dig even deeper from a previous post on pizza by studying a few concepts I have included within the Classic Science:  Physical Science curriculum.  Let’s see how our four main concepts of science relates to the concepts of heat and temperature…

Okay…

It is dinner time and you are very hungry! Your pizza just got out of the oven and you are ready to eat!

You let it rest on the plate for a few minutes to cool off…

You carefully grab the crust and you find that it is not too hot.  So you pick up the pizza and take a huge bite out of your slice…

OWWW! The pizza sauce is still too hot!

How could this happen?  The crust was fine, but the sauce was still too hot! I am sure you will understand what is going on after we take a closer look at two scientific concepts:

Thermal Energy and Heat

Before we jump into these new concepts, let’s review a few things:


ATOMIC PIZZA ON THE MOVE…

Everything in the universe is made up of ATOMS which are always in motion.  That’s right!  If you could see every atom within your pizza you would find each of them moving around a bit.  Even the atoms that make up the solid crust would be vibrating in place!

All of this motion can be measured just like everything else in the world!  Scientists call the measurement of energy in moving atoms – thermal energy.  The cool thing about thermal energy is that it can move too!

What we call heat is really the movement of thermal energy from a hotter object to a colder object.  This means that energy, like ATOMS, can go through DIFFUSION!  Another way to say this is: Large areas of ENERGY tend to move to areas that do not have as much ENERGY.

HOW DENSE IS YOUR PIZZA?

The DIFFUSION of heat energy depends on a lot of different factors.

One of these factors is the DENSITY of the object that is transferring the energy!  Some objects (like the water within your pizza sauce) can hold onto a lot more energy than other objects (like the crust of your pizza.)

It is the different DENSITIES between the sauce and crust that causes the four-alarm fire in your mouth when you bite down into your pizza!

Let’s take a closer look at that slice of pizza again!

When you pulled your pizza out of the oven, the crust and the sauce was at the same temperature. This is because you pulled them both out of the same oven at the same time!

But even though both the crust and the sauce are at the same temperature …the sauce has more thermal energy inside it!

When you bite into the pizza, thermal energy DIFFUSES between the pizza (higher temperature) and your mouth (lower temperature).  Since the sauce has much more thermal energy to give off,  it burns you!  OUCH!

THE LAW OF CONSERVATION… OF PIZZA?

It is true that the LAW OF CONSERVATION states that ATOMS cannot be created or destroyed, only rearranged.   However, this law also applies to energy as well…

The LAW OF CONSERVATION of ENERGY states that ENERGY cannot be created or destroyed only moved from one place to another.

This means that none of the energy from the pizza that burned the roof of your mouth was destroyed.  It only moved from the pizza INTO your mouth.  See, doesn’t that make you feel better?  Now, if you don’t mind, all this talk about pizza has made me a little hungry.  I’m out of here!

Check out the Classic Science:  Physical Science curriculum to learn more about ATOMS, DENSITY, DIFFUSION, and the LAW OF CONSERVATION!

Also be certain to subscribe to Mr.Q’s blog every Thursday to learn more about how to teach science with cheap, everyday items!




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How To Teach Science During Dinner… With Mac and Cheese

March 25, 2010
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Whether it comes from a box (ewww…) or is made from scratch (oh yeah!) you have to enjoy the cheesy goodness of the ever-popular…

Macaroni and Cheese!

I’ve put down more bowls of this gooey comfort food than I can count.  Despite the MASSIVE amounts of recipes out there (I received nearly 700,000 results from an Internet search for “Mac ‘n Cheese Recipes,) there is still ONE ingredient that remains the same in all of these dishes… the macaroni.

This week, we are going to take a look at what goes on inside our favorite curved pasta.  Before we do, be certain to check out the four main concepts you’ll need to explain the science behind Mac and Cheese:


Most of the macaroni you see either in a bag or stuck to a piece of artwork on your refrigerator door is nothing more than a hardened mixture of wheat flour and water.  In two previous posts, you learned that wheat flour is made up of many different molecules (aka – groups of ATOMS).

The majority of wheat flour (about 70%) is made up of an amazing group of molecules known as starch.  And after you add water to flour, large molecules known as gluten make up most of the remaining 30%.

Now when you place the uncooked macaroni into a pot of boiling water, all sorts of cool things start to happen!

We learned all about the science of water within the post on How to Teach Science During Breakfast…with Coffee.    Basically, the molecules within the boiling water receive a HUGE amount of energy from the stove.  This DIFFUSION of energy from the stove, onto the pot, and into the water causes all of the water molecules to start moving around a lot.

You’d move around a lot too if there was a fire under you?  I bet you would!

There is a lot more DIFFUSION going on when the macaroni finds its way into that boiling pot of water.  As soon as the pasta gets into the water, the starch within the macaroni starts to absorb some of that hot water.  Another way to say this is:

The water molecules begin to DIFFUSE into the starch.

What does that moving water do to the DENSITY of the pasta?

Nothing!

Density is defined as the amount of atoms found within an object (of a particular size.)  This means that every uncooked piece of macaroni has a measurable density.  But if you have ever spent time cooking pasta, you would know that pasta SWELLS as it is being cooked.  Since its size increases, its density will remain the same.

Don’t fall into the trap that so many people do!

You may BELIEVE that the swelling pasta is actually making new atoms to cause its increase in size.   BUT THIS IS NOT TRUE!   Remember the LAW OF CONSERVATION:

Atoms cannot be created or destroyed, only rearranged.

The swelling of the pasta is simply the diffusion of water molecules into the starch molecules!

Anyone can take out a box of instant macaroni and cheese, cook the pasta, and dump that weird-looking “cheese powder” into the mix.  But as we all know, good food takes time to prepare.  Below is my recipe for homemade Mac and Cheese.   I promise that once you try this recipe, you’ll never buy another box of “mystery powder” cheese in a box again.  Cheers!

Mr. Q’s  Macaroni and Cheese

1 pound elbow macaroni
1 stick unsalted butter
5 Tablespoon flour
3 (12 oz) cans evaporated milk
1/8 teaspoon ground nutmeg
1 teaspoons dry mustard
2 teaspoons hot pepper sauce
2 cups extra-sharp cheddar
1 ¼ cups American cheese
¾ cup Monterey Jack
¼ cup Bread crumbs
¼ cup Parmesan cheese

Cook macaroni in plenty of water and drain.  Set is aside for a bit.

Melt ½ of the stick butter until foaming.  Stir in flour and cook (about a minute with CONSTANT stirring) until the mixture turns brown.  Wisk in the evaporated milk, nutmeg, dry mustard, and hot pepper sauce for 3-4 minutes until mixture is slightly thick and simmering.

Remove pot from heat and stir in the cheeses and ½ cup of hot water.  Stir until the cheeses melt, then stir in the macaroni.

Top with mixture of ¼ cup bread crumbs, ¼ cup Parmesan cheese, and ½ stick of melted butter.  Bake at 350 degrees for 20(ish) minutes in 9-in baking dish.

And, as always, good food takes time so….

SLOW DOWN and let this bubbly meal sit for 5-10 minutes before you eat!

Find out more about scientific concepts for your family within the Classic Science Curriculum

Be certain to check back every Thursday or subscribe to the Blog of Mr.Q for weekly updates.


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How to Teach Science During Dinner… With Pizza!

March 18, 2010
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Oh yes.  Pizza.  What more can be said?  Most of us have tried many different kinds of pizza and have found at least one favorite for the dinner (or breakfast) table.

So this week, let’s pull a little information from my Classic Science Chemistry book and dig into a little of the science behind this tasty item.  Rather than focus on the science of MAKING a pizza, let’s look more at the science of EATING our pizza.  First of all, let’s review some of the basic concepts we will be looking at from our previous series on the Science of Breakfast:


As you already know, pizza (like everything else in the universe) is made up of atoms.  And atoms usually do not just hang around by themselves.  They stick together with each other to form a larger group called a molecule.  Pizza is filled with billions of molecules!

This fact is both good and bad for us.  You see, our bodies need many of the atoms within these molecules to live.   That’s right!  We use these atoms to help us move, breathe, walk, talk…

But there is a HUGE problem!  These atoms are stuck together in such LARGE molecules that our bodies cannot use them.  Another way to say this is the density of our pizza is too large.  There are too many atoms stuck together in that piece of pizza for our bodies to be able to use them. We need to move them away from each other!

But how?

This is where our digestive system comes in!

First, let’s imagine you are eating your favorite kind of pizza. Once that pizza gets in your mouth your teeth get to work.  They grind your pizza into smaller and smaller pieces. By doing this, your teeth start to break down a lot of the large molecules into smaller molecules!

This means your teeth help to diffuse the molecules within the pizza away from each other!  This makes your slice of pizza less dense.

But the molecules that make up your pizza still need to break apart even more! This is when your body starts to attack your food with chemicals called enzymes (“en-zimes”). Enzymes are chemicals made by your body to do all kinds of cool things. Some enzymes are made to help break down the large molecules in your food!

Now if you want to get REALLY gross, you can open your mouth and look at all of that mushed up goodness that was once your pizza.  (Please don’t do that at the dinner table…)

You might be thinking with all of that grinding and tearing from your teeth AND the chemical warfare you are waging against that squished up goo swimming in your mouth that SOME of the atoms within that pizza HAVE to be destroyed, right?

WRONG!

The Law of Conservation states that atoms cannot be created or destroyed, only changed.  That means all those atoms within your pizza are still hanging around inside your body (unless, of course, you left a few crumbs on your cheek.)

Imagine a slice of pizza built out of building blocks.  You could easily take apart that artistic masterpiece with a little effort, right? Of course you could.  Well THAT is what you are doing your pizza with your mouth!  You’re not destroying anything at all, just rearranging the pieces.

I’m not done yet!  We’ve got a lot of science to look at during dinner.  Stay tuned!

Find out more about scientific concepts for your family within the Classic Science Curriculum

Be certain to check back every Thursday or subscribe to the Blog of Mr.Q for weekly updates.




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