Body Systems: Skeletal System: Why You Need Calcium

For this demonstration, you'll need a clean chicken bone* (a drumstick works best) and a large jar filled with vinegar.  You'll also want some way to close the jar, either a lid or some plastic wrap.

Observe the bone, try to bend it (but don't actually do so, you want to keep it in one piece).

Place the bone in the vinegar and cover the jar.

Remove the bone from the vinegar every day for about a week.  Observe and test for flexibility.


Over the course of the week, the bone will become more and more flexible, taking on a rubber-like feel by the end.  The vinegar (acetic acid) breaks down the calcium deposits in the bone, allowing you the opportunity to observe the importance of calcium in maintaining bone strength.

**The next time you have chicken or turkey, you may want to clean the bones and stick them in a resealable bag in the freezer, so you have them when you need one.

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The Importance of Brushing Teeth - Part II

Last week we examined the importance of brushing your teeth as a preventative measure to defend against the acid found in foods.  This week we'll examine another way in which regular tooth brushing prevents problems - preventing tooth stains. 

This experiment is run much the same way as last week's.  You'll cover an egg with toothpaste, let it sit overnight and wash off the toothpaste the next day.

The egg is then placed in a cup of coffee (or strong tea).  A second, untreated egg is placed in a second cup of coffee.

The eggs are then allowed to sit and are observed over the course of the next 24 hours - or even longer if you wish.

You will notice that the untreated egg develops darker stains and develops them more quickly than the treated egg. 

You'll also notice that the treated egg does develop stains - the toothpaste does not completely prevent that from occurring, it just slows it. 

Untreated



Treated with toothpaste



So, when you brush your teeth,, you're building up protection against future stains as well as removing older stains.

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The Importance of Brushing Your Teeth - Part I

We've previously looked at the importance of brushing teeth to remove stains that certain foods may leave on the teeth.  This week and next we'll examine the importance of brushing teeth as a preventative measure.

The fluorine in toothpaste binds with calcium in your teeth to form calcium fluoride, which strengthens your teeth.

For this experiment, you'll want to make sure you use a fluoride toothpaste.  You'll see it listed in the active ingredients as sodium fluoride.

To represent our teeth, you'll be using an egg, as the shell is made of calcium, as are our teeth.

Coat one egg with toothpaste - all over.  Allow the egg to sit overnight with the toothpaste on it. 

The next day, wash the toothpaste off the egg.  Then place that egg in a cup/beaker of vinegar.  Place a second, untreated egg in a second cup/beaker of vinegar. 

The vinegar is an acid, as are many of the foods we consume, including, but not limited to fruit, tomatoes, and soda.

Observe the eggs over the course of the next 24 hours. 

You will notice that the cup with the untreated egg develops a foamy white substance on the top of the vinegar in a fairly short amount of time.  That foam is made of dissolved calcium - the shell is dissolving.  The treated egg does not produce nearly so much.

After 24 hours you'll notice that the untreated egg has completely lost its shell - you're left with a squishy egg.  The treated egg has a small amount of shell left.  It's on the squishy side - the fluoride doesn't completely protect it.  That's one of the reasons why you need to continue to brush your teeth - to constantly provide more fluoride and to help wash away the acid currently in the mouth.  It's also important to note that even with regular brushing, eating a diet high in acidic foods will, over time, wear on your teeth.  And lots of acidic foods without brushing your teeth is a recipe for ruining your teeth.

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Soda, Tea and Your Teeth

Soak an egg* in Coke or tea overnight.

Show your students a plain egg and the egg soaked in the Coke/tea - that's what the Coke/tea does to your teeth over time.

Then, use different brands of toothpaste and toothbrushes to try to clean the eggs.

 *You may want to hard boil the egg, in the name of reducing the mess which will occur if students get a bit carried away with their brushing.

FYI I used a brown egg, which makes the stain appear extra dark, and makes it harder to tell when you've brushed it off.  For students, I would use white eggs, but for the purpose of taking pictures for this blog, I used what was on hand. 

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Total Cereal: Iron Fortified

This activity can be used for several different curriculum areas: elements, magnetism and nutrition

Back in the day, Total cereal used to run a series of commercials in which a person had to eat a large number of bowls of their favorite cereal in order to get the same amount of vitamins and minerals they could get in one bowl of Total.  One of those nutrients is iron.  Check out how they fortify their cereal....

Pour some cereal into a cup or bowl.  Pour some water on the cereal and let it sit for 15-20 minutes; enough for it to get nice and soggy and too gross to eat.

Place a magnet (use the strongest magnet you can get your hands on - a regular magnet works, but the stronger the magnet, the better the results) in a plastic baggie*.  Then, use the magnet to stir up the cereal sludge.

When you pull out the magnet, you will find that you have small pieces of iron sticking to the magnet!  The cereal is fortified with iron filings!  Perhaps not the most usable form of iron for your body, but iron none-the-less.

*Putting the magnet in a plastic baggie serves 2 purposes:
 1 - It makes clean-up a LOT easier!
 2 - It can be hard to see the iron pieces on the magnet, but if you pull the baggie off and place it on a piece of white paper, the iron will be easy to spot!

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