Standards that are meant to inform teachers about what to focus on in classroom science classes include references to materials and their properties. Understanding the concept of materials is fundamental in science. For young children, this translates into identifying what things are made of and answering the question of how they know something is, for example, paper, stone, or glass. You can distinguish a material based on its properties, or those things that make it special or unique.
Which brings us to metals. Metals make up 80% of the elements included in the Periodic Table, so clearly there should be an infinite number of opportunities for identifying them in our environments and as materials that things are made of. Elements cannot be chemically broken down into simpler substances or other elements. Elements are also the primary ingredients of matter. Noticing and labeling metals is the first step for young children – a step that is foundational for basic chemistry. Yes, chemistry, but don’t try to go too fast. Just help your young child to notice and label these materials in your home, the yard, your car, and as you drive and walk around your neighborhood or town. Think of the bridge you cross, the stop sign, your lawn mower, or their bicycle. I spy with my little eye, something made of metal….
Before we begin it is worth noting a few key pieces of information about metals that will be helpful to you in your role as a guide. I don’t think the following characteristics should be your focus or drive conversations, but should an opportunity arise, you can begin to introduce these distinguishing properties.
Metals are distinguished from nonmetals in that they have the following characteristics:
- Luster – Metals are shiny when cut, polished, buffed, or scratched.
- Ductile – Metals can be shaped into wires
- Malleable – Metals are strong but can be pounded into sheets
- Metals are solid at room temperature (except Mercury which is liquid at room temperature). They can be heated to high temperatures without melting.
- Metals conduct heat and electricity
- Metals react to oxygen and acids
These features will be explained in more detail below, but bearing them in mind will be helpful as you introduce your child to magnificent metals.
Also, for your information, metals such as pure gold, silver, copper, and iron are elements (elements consist of one type of atom). Metal alloys and compounds also exist. Bronze is a compound or a mix of copper and tin. Brass is a compound of copper and zinc. Steel is an alloy or a mixture of chemicals where at least one of them is a metal. Steel is a mixture of iron and carbon. Pewter is also an alloy. Pewter today is made with tin, copper, and antimony. Historically pewter was made with lead, and when the lead leaches into solution it is poisonous. Some Colonial Americans, particularly those who were wealthy, suffered from health problems related to the ingestion of lead from their pewter cups and crystal goblets, as well as lead from some ceramic glazes adorning their plates.
Once again, these more advanced chemical concepts may be less important at this time than developing an awareness of the prevalence of metals in our lives and their uses. For simplification, we will refer to pure metals, metal compounds, and alloys as “metal” in this exercise, rather than constantly distinguishing the three.
What metals can you see right now?
How can you tell if something is made of metal? What are metals used for?
What are the different kinds of metals?
How many different kinds of metals are there?
Where do metals come from?
Why would you choose metal, as opposed to paper or clay, when making something like a cooking utensil or a tool?
Invite your child to find an example of something made of metal in her room, the kitchen, or another room in the house. Examine the metal by looking at it and finding the words to describe it. Touch it and again find words to describe what it feels like. Taste and smell it if safe. Tap on it with a finger, a stick, pen, or another available object. Does it make a sound? Describe the sound.
Repeat these observations, finding alternative examples of metals and novel descriptive terms.
For a new adventure, take a trip to a hardware store and look for metal. If you have a hardware store shopping list including items made of metal, devise a scavenger hunt.
Aluminum foil presents a good opportunity to explore the notion of malleability or flattened to a sheet. Roll foil into a ball and observe with all the senses, then unroll it or flatten the foil out and observe again. Does it look, feel, smell, taste, or sound different before or after?
If you have an old-fashioned thermometer invite your child to examine it and find mercury. What does mercury look like? Place the thermometer (if clean) under your child’s tongue or armpit to take her temperature. What happens to the mercury? Why? How do you make the mercury go back down? (Hint: you have to shake it). If the thermometer has red liquid, that is most likely alcohol.
Compare and Contrast
If you can collect examples or small pieces of various metals (and compounds or alloys), then invite comparisons of color, luster (shininess), or the types of things that a metal is used to make (cars, silverware, jewelry, toys, electronics). Coins, either the US or better yet International currencies, can also be examined and compared.
An obvious place to start with comparisons is metals and nonmetals, or metals versus paper, plastic, wood, glass, or fabric.
Consider comparing metals as non-living materials to materials that are made from things that were alive, leather, bamboo flooring, paper or other products from wood.
Collect nails, bolts, nuts, and screws. Observe, describe, compare and sort.
Counting is a good place to start. Count pennies (since 1982 made mostly of zinc) versus dimes (copper and nickel alloy) or other coins.
A balance scale can be used to compare the weights of various coins or the other metals in a collection. Which weighs more, a penny or a nickel, a nickel or a dime? How much aluminum foil equals the weight of a quarter, a steel nail, or a bolt? This exercise is really a proxy for measuring the weights of the metals, as the weight is confounded with the size of the object. Having said that, it can be fun to compare the weights of these different objects made of metal.
Find several different spoons in your kitchen, such as a plastic spoon, a wooden spoon, a silver spoon, a silver-plated spoon, or other metal spoons. Place these in a bowl or glass filled with hot (but not scalding) water. Leave them in the water for a minute. Touch their handles and determine whether or not you can detect a temperature change or if the handle is conducting heat. Which type of spoon is the warmest and the best heat conductor?
Extend this experiment by predicting which metals outside are conducting heat provided by the sun. Touch equipment on the playground, or metal inside of a car that has been parked in the sun. Which metallic parts will be warm (or even very hot so proceed carefully- Seatbelt clips can be very hot!)
The most common experiment for children involving metals is to create a chemical reaction of oxygen and iron. What happens? When oxygen and iron unite, the result is rust. There are variations on this experiment. You may already have a steel wool pad by your sink that is rusting. If so, invite a close look and ask for an explanation of what happened compared to a new pad out of the box.
If you do not have a steel pad already showing signs of rust, place a new dry one in a plastic bag and seal it. Next, put a second pad that has been placed under the faucet and is wet in a plastic bag and seal it. Now, wait a couple of days, checking those bags periodically (every couple of hours). What happens? Look for rust on other objects inside and out. What are those objects made from or what type of metal rusts (iron)?
Another popular experiment is to clean a copper penny. Find some vinegar. White vinegar may be the best as its effect on the penny may be the easiest to observe because the liquid is clear. Pour the vinegar into a jar until it is about half full and add a teaspoon of salt. Next drop pennies, you chose how many, into the vinegar-salt solution. Watch what happens.
Some of those pennies can be removed from the solution, rinsed off with water and dried. Remove other pennies but do not rinse them. For the first batch that were removed and rinsed, you now have clean pennies. (The acid-salt solution removes copper oxide, which makes the pennies appear dirty). For the second batch that was removed but not rinsed, a different type of reaction should be observed. When oxygen combines with the solution remaining on the pennies, a bluish-green color should appear. Compare the results with newer pennies versus pennies minted prior to 1982. Older pennies contain considerably more copper.
You can mix up this experiment by adding other coins to the solution, or nickels, dimes and quarters. Do you get the same results? Why or why not? Check the dates on quarters and dimes. Those minted in 1964 or that are older are pure silver and worth more than the coin itself. The more recently minted quarters, nickels and dimes are all alloys or a majority of copper with some nickel.
After removing the pennies, add a clean iron nail to the solution. You can clean a nail with a cleaning powder or steel wool cleaning pad. Copper atoms from the pennies should form a compound with the vinegar and when the nail is submerged the copper suspended in that solution coats the nail. After adding the nail, wait several hours. When it is time to remove the nail, do so carefully looking for any changes in color. Try this with bolts or screws of different metals. What happens? Invite your child to think of other things to try. This process is a type of metal plating. Do you have any silver-plated tableware or cutlery? Metal plating is the process where a thin coating of one kind of metal is deposited on another surface.
Another common experiment is to create electricity with a lemon and two different metals. An electric battery needs an acid, and lemon juice is critic acid. For the metals, you can use a paper clip and a piece of copper wire. Straighten one end of the paper clip and insert it into the lemon. Next insert the copper wire into the lemon, removing any insulation from both ends if that is an issue. Hold the two metals, the paper clip, and the copper wire, inviting your child to touch her tongue to both simultaneously. She should experience a tingling sensation. Try this with her finger, touching the two wires that are still in the lemon to her finger. What it the difference in the sensations experienced when you use your tongue versus a finger (one is wet and water conducts electricity)? Now might be a good time to remind your child not to insert metal objects (or anything for that matter) into electrical sockets.
Explore healthy eating habits and the importance of metals in our diets. Believe it or not, our health depends on consuming trace elements of metals, including sodium, calcium, iron, zinc, copper, magnesium, chromium, and molybdenum. These metals are essential to our physiologies (see table below for a few examples).
In these discussions, please be VERY clear, that these elements are consumed by eating a variety of regular FOODS, not eating metal outright. A good exercise would be to read labels on various food items, looking for these metals as ingredients. Here is some information on different minerals, their function, and food source:
Sodium: Helps fluid balance, nerve transmission, and muscle contraction. Found in table salt and soy sauce.
Potassium: Helps fluid balance, nerve transmission, and muscle contraction. Found in meats, milk, fruits, and grain.
Calcium: Helps keep bones and teeth healthy, influences muscle and nerve functioning, blood pressure and immune system processes. Found in milk and milk products, soy, greens, legumes, and fish.
Iron: Important for red blood cells that carrying oxygen, energy, and metabolism. Found in organ meats, red meats, legumes, leafy greens, egg yolks, shellfish, poultry, and fish
Zinc: Needed for making protein and genetic material, has a role in taste, wound healing, normal growth and immune system health. Found in meats, poultry fish, leavened whole grains, and vegetables.
Metals are part of the earth’s bounty. Mining produces metals, although recycling is increasingly a source of metals for manufacturing. I have seen a bumper sticker that says, “If it can’t be grown, it must be mined.” Mining, however, can be a controversial topic. Mining is essential because, as you and your child should have noticed by now, a majority of the things we use to cook, to get to school or work, for entertainment, and in the construction of the buildings we occupy, are made from metals. Yet mining has not always proceeded in ways that conserve and protect the earth. Take some time to look at websites and books that explore this important issue and engage in a discussion learning to understand the pros and cons of mining. For the sake of argument, mining minerals or metals is not the same as fossil fuel, or oil and gas, extraction.
Explore how to stop things from rusting. Paint, grease or oil can protect the metal and keep the oxygen from touching it. Stainless steel includes chrome and nickel and these metals do not rust.
Explore magnets and metals. Magnets and magnetism will be the topic of a separate post, but if you have a magnet and anything that is made from iron ore (steel) available, let the discovery process begin.
Examine with your child the materials used in jewelry. Explore what karats are or the term used to describe the purity of gold. Twenty-four karat gold is 99.79% gold (Note: Karat is the term referring to a metal’s purity, while carat refers to a gemstone’s weight). What is white or rose gold? If you do not own samples of these, see if you can find examples next time you are in a department or jewelry store.
Look up what is meant by the historical period referred to as the Bronze Age.
Do you recycle in your household? Find resources with your child that explain what happens with the aluminum or tin cans you recycle.
The United States Mint has a website explaining how coins are made. If you or if you know someone with a collection of coins, perhaps your child could examine different pieces in this collection and then explore online or in books how the metal content of coins changes over time.
Make sculptures with tin foil, wire or coat hangers. Explore how metal is used in sculpture or the process of casting. Gold leaf also plays a role in art and the decorative arts. Find pictures of paintings by Klimt (or if you are near a museum lucky enough to have a Klimt in their collection arrange a visit). Explore the uses of gold leaf in decorating interiors of rooms, furniture, ceramics, or other objects over time.
Visit with a blacksmith or find a book exploring this trade.
Visit a silversmith or find a book exploring what they do and the beautiful jewelry they make.
The metals: Gold, Silver, Copper, Zinc, Nickel, Iron, Steel, Brass, etc.