Jan/14/2015
Earth Science / health / kitchen science

Start with Salt

Being stuck indoors because of cold or wet weather is not an excuse for ignoring topics in earth or physical sciences. In your kitchen, there are several ingredients that can be “mined” for information. Let’s start with salt.

 

Salt is a basic ingredient in cooking. While there is much written about limiting salt in our diets relative to our health, it is a nutrient we cannot live without. It origins are fascinating as are its capacity to inform understanding of principles of chemistry. Salt is a familiar element that can easily be taken for granted, but discussions of salt can for valuable learning.

 

Before you get started please review the What is Guiding Curiosity page so you understand the logic of the suggestions below and understand how to be a guide. Remember this is not a recipe that you walk through, but rather suggestions for how you might extend a conversation or a play session, adding learning to the mix.

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Questions

Start with questions.  Ideally, listen to what your child is curious about, or add your own…”I wonder……..?”

 

What is salt?

Where does it come from?

Are there different kinds of salt?

How and why is it used in cooking?

How does it affect our bodies?

Where does the salt in the ocean come from?

 

(This is salt on the shores of the Dead Sea)

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Observe

Follow your child’s lead. What is she looking at or interested in?

 

If you have different types of salts in your kitchen, or sea salt, Kosher salt (which is mined from dried up sea beds or oceans), or table salt, pour small amounts out and look carefully at the shape or size of the particles and color. A hand lens may help. Do they taste different? Can you see a crystal?

 

Himalayan salt

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If you have unrefined sea salt, you may be able to see other minerals that were also left behind when the salt was harvested from the sea and the water evaporated.

 
 

Compare/Contrast

If interest is maintained in salt, here are some next step suggestions.

 

Fill a jar with water about a third full and ask your child to tell you what it looks like. Next, mix in some amount of salt. Perhaps begin with a tablespoon, but ask your child to decide. Add the salt to the water and observe again. Now, what does the water look like? Add more salt, stir, and observe what the water looks like. What changes? If you have more than one type of salt available, mix the different types with a small amount of water in a clear container. Shake or stir so the salt dissolves. Does water look different depending on which type of salt was added?

 

Find photos of foods that are preserved with salt, or pickles, kim chee and sauerkraut (salt is used to kill bacteria on cabbage, but fermentation is the real process), cured meats (salmon gravlax, salt pork/bacon, ham, salt cod), and cheese (salted for flavor and to slow bacteria down). Photos can be classified as involving animal or vegetable products, whether your child has tasted that food or not, and whether or not he liked it a lot, a little, or not at all.

 

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Many high-end grocery stores carry a variety of salts from different parts of the globe and derived either from evaporating seawater or from mining rock deposits (both under and above ground). Examine and compare these products (in the packaging) in the grocery store. There is no need to purchase unless curious to try them at home.

 

Compare amounts of salt listed in the ingredients of favorite foods.

 

 
 

Measure

Some kids are going to take to measuring things and others not so much.  Can you tell which kind of kid you have and if measuring things is an interest, make the tools available and see where it goes.

 

If you have different kinds of salt at home, or table salt and Kosher salt, compare their weight. Measure out a teaspoon of each and weigh these by pouring onto the scale directly or subtracting the weight of the container. Are they the same?

 

Some salt crystals may be large enough to measure a side with a ruler.

 

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The World Health Organization suggests that we not consume more than 2000 mgs of salt a day or 2 grams. If you have access to a scale that can measure out these amounts, do so. Otherwise consider a balance scale comparing other daily supplements or vitamins that are listed as weighing a specified amount on one side and salt on the other. A visual image of how much salt is recommended for daily consumption is helpful in sticking to those recommendations.

 

 
 

Experiment

Again, some kids like to tinker.  The following are ideas for how you may encourage that tendency.

 

Fill a glass with water and ask your child to take a sip and describe what it tastes like. Take a spoonful of salt and after describing what it looks like, empty it into the glass of water, stirring until the salt is dissolved. Ask your child to sip again, describing the taste. Where did the salt go? Why can’t I see it but I can taste it? Compare this process with pepper, sugar, flour and other substances. Not every item in the kitchen dissolves.

 

 

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Perhaps your child has noticed how much easier it is to float in the ocean versus a swimming pool. That is because salt water is denser than fresh water, and more easily buoys an object up, including us.

 

Here is an experiment that you can vary to determine how salty water has to be to make an object float. Start with a bowl of water and several objects that usually will sink in water, but perhaps not so heavy that they will never float. These objects must also fit inside of the bowl you will fill with water. Often this experiment is done with an egg but look around for pebbles, shells, marbles, or fruits such as berries and vegetables like pea pods. Fill a small bowl with water and add a tablespoon of salt, stirring it in so it dissolves. Place the objects on the water. Which float and which sink? Now add another tablespoon of salt and experiment with your objects again. Keep going until at least some of the objects float. Keep a chart of how much salt is needed before an object floats.

 

Add a measured amount of salt (2 tablespoons) to water (1/4 of a cup). Stir this concoction and pour it into a shallow dish or on a plate that is then placed in the sun. Wait for a couple of hours (or days depending on the weather). What remains after the water has evaporated? Is it the same amount of salt you started with? To make this more interesting, you can pour the saltwater solution over rocks or shells. You can also add food coloring to grow colored crystals. Another alternative is to paint the salted water onto black construction paper and let the “paint” dry. For this latter activity, very salty water will leave behind more of a “picture.” So create solutions of varying salt content for differences in the color on the page.

 

Try your own brining experiment. Take two chicken breasts of approximately the same size. If you can weigh them do so separately, making note of the result for each. Place one chicken breast in plain water. Place another in water with salt added and dissolved (for two cups of water consider a tablespoon of salt). Allow the chicken breasts to soak for about one hour.   Weigh a second time comparing the before and after weights of those breasts. Is there a difference? Which is heavier after being in water? What happened? (The salt in the water changes the protein causing it to absorb more water, thus increasing “water weight”.)   Roast these two breasts in the oven at approximately 350 degrees for approximately 20 – 25 minutes. Keep track of which breast was brined or soaked in the salt water. Do a taste test once they have cooled enough to eat. Is one juicier? The brine of salt water not only causes the breast to absorb more water but also to retain it, this should result in more tender meat.

 

This experiment can be repeated by adding more or less salt to the brine.   Pork chops can also be brined.

 

When cooking meat you want to preserve moisture for tenderness. When cooking vegetables you want to remove excess moisture so you do not end up with a soggy mess. If preparing eggplant, you may be familiar with salting it first to draw out moisture. If the excess moisture is not removed, the eggplant can absorb excess oil because of air bubbles. If the liquid is removed those air pockets collapse. Try an experiment with two slices of eggplant. Salt one and not the other. Place a paper towel on top of both of them and then a weight such as a heavy pan. Wait for a couple of minutes then remove the weight. Which slice produced the most liquid?

 

Take some ice cubes from the freezer and shake some salt on them. What happens? Dissolve some salt in water and pour this onto the ice. What happens? How is this information useful? What can you do with the knowledge that salt can melt ice?

 

Take two identical plastic glasses and fill them with the same amount of warm water (1 cup). Add salt (2 tablespoons) to one of the glasses and stir to dissolve. You could add a drop of food coloring to one of the glasses to remember that it is either the fresh or salt water, now place them in the freezer. Come back in about an hour. Examine the two glasses for similarities of differences? What do you see? This can be repeated by making the salt water in the second glass even saltier. Keep track of amounts of salt and results. Do not use glass containers as they will freeze and break.

 

Try a salt taste test on your child’s tongue. Invite your child to look at her tongue in a mirror, preferably a magnifying mirror. Ask her to describe what she sees. Those bumps are called papillae, and the contain taste buds. Scientists know that taste buds are designed to distinguish only five basic tastes: sweet, sour, salty, bitter and umami. Find the area of the tongue that is designed to taste salt by dipping a cotton swab in some water and then in salt. Touch different parts of the tongue with the tip of the swab and see where the salt is detected. You can complete this series by doing the same with vinegar, sugar, unsweetened cocoa (bitter), and soy sauce (umami). Use a different cotton swab each time. Also, rinsing out the mouth between each taste test and starting with a clean slate, is a more controlled scientific experiment. Create a map of the tongue.

 

You can create a desalination device for saltwater using easily accessible items. Mix water and salt in a larger mixing bowl until the water tastes salty. In the middle of that bowl place a jar. The jar will be standing in the salt water, but the salt water should not be so deep that it spills into the jar. Also, the sides of the bowl should be higher than the top of the jar. Place plastic wrap over the bowl creating a tight seal around the edges. Next place a small object, such as coins or pebbles, in the middle of plastic wrap so it sags. The sag or dip in the plastic should be just above the jar. Now, finally, place the bowl on a windowsill or shelf that receives sunlight. Wait and watch what happens. When there is sufficient water in the jar in the bowl, taste it. What happened? (The heat from the sun makes the water evaporate. The rising water vapor reaches the plastic and condenses. The fresh water on the plastic will flow to the sagging area above the jar and drop in.)

 

Do a taste test. Make a recipe with more or less salt in it. For example, if you eat vegetables with a dip, create two versions one of which has more salt added.   Which do people prefer? Make a bar chart. (Hypothesize that moderate amounts of salt will be most preferred).

 

Salt cod

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Elaborate/Glossary

Look up the use of salt for medicinal purposes. For example, salt is an ingredient in Pedialyte and sports drinks to replace electrolytes after vomiting or sweating. Epsom salt is recommended for soaking sprained ankles.

 

Look up the historical use of salt in medicine. There are a thousand years of history of the use of salt. Hippocrates (think Hippocratic oath) used salt in a variety of ways including as a topical for skin lesions (ouch, hurts to think about that).

 

Salting is the oldest form of preserving foods (before refrigeration). It has been used as a form of currency in trade, and historically was a central part of work and life. Given its prominence, keep your eyes open for descriptions of how salt is used in literature or artwork.

 

If you live in a city where salt is used during winter storms, explore why with your child. Ask what the salt is doing or how it works? Take a look at the salt that is used…make sure that tasting is not part of this observation. (The salt does not actually melt the ice, but lowers the temperature at which water freezes. The specifics of this are less important than the fact that salt effects of freezing of water).

 

Salt is used in a variety of rituals worldwide. Sumo wrestlers sprinkle salt in the ring prior to their matches. The Egyptians used salt in the mummification of the dead. Look up more ways that salt is used in ceremonies.

 

 

Salt played a role in a number of geopolitical conflicts historically.  (http://beyondtheshaker.com/pages/Salt-Guide-Politics.html)

 

What is meant by cloud seeding?

 

Salt is sodium chloride or NaCl (table salt is 97% – 99% NaCl, the rest is other additives or minerals). Look up the symbols Na and Cl on a periodic table. A molecule of salt contains an equal portion of Sodium and Chloride as compared to a molecule of water that is two portions of Hydrogen and one of Oxygen, or H2O.

 

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Glossary: Use these terms often. You may not hear your child repeat them, but they are sinking in.

 

Dissolve

 

Evaporate

 

Sodium

 

Chloride

 

Dehydrate

 

Boiling

 

Freezing

 

Buoyant

 

Crystal

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