How To Teach Science During Dinner… With Mac and Cheese

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

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.

Tags: atoms, Classic Science, cooking, density, diffusion, dinner, law of conservation, science