Protein, Carbohydrate, Fat Worksheet

Your middle school students will compare proteins, fats, and carbohydrates.

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Nutrition, Health, and Safety Unit Study

Protein Carbohydrate Fat Worksheet

Objective: Compare carbohydrates, proteins, and fat.

MatchCard: Download below.

MatchCard Information Pieces describe characteristics of fats, proteins, and carbohydrates. Students match the pieces to the correct nutrient.

Print the MatchCard

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This is MatchCard #3 of the Nutrition, Health, and Safety Unit Study. Find more information on MatchCard Science below.

Carbohydrate Molecules

carbohydrate molecule diagram

Students already learned about carbohydrates in MatchCard #2. Review the information and activities on this MatchCard before continuing with these activities.

Marshmallow Carbohydrate Molecule

Carb models can be built with different colors of large and small marshmallows. Use one color of large marshmallow for carbon and a different color for oxygen. Use small marshmallows for hydrogen molecules. Toothpicks are used to join them.

If you can't find commercially colored marshmallows, I have found the easiest way to dye them is to roll them in a few drops of food coloring and let them set on wax paper to dry.

An alternative is the coin method described next, which makes a fast and fun memory game. Whether you use the marshmallows or coins, keep the materials handy for another project with proteins.

carbon protein and fat molecule marshmallows
You will need 6 large carbons, 6 large oxygens, and 3 large nitrogens. You will also need 12 small hydrogens.
carbohydrate molecule diagram
Make the carbohydrate molecule. Take a pic and save the marshmallows for the activity below.

Memory Money Molecules

Use nickels for carbon, dimes for oxygen, and pennies for hydrogen in this exercise. Have the student(s) silently study the carbohydrate molecule for one minute. Then, without looking at the illustration, see how fast they can make it with the coins.

Fill 'er Up

Where does your energy come from?

Calorie Gas Pump

We have already learned that carbohydrates are a source of energy for our cells. Just as some appliances can use either batteries or electricities as an energy source, our cells can also other energy sources besides carbs. Let them quess what the two other sources of energy (calories) are. Carbs have 4 calories (Teachers Note: technically kilocalories) Proteins also have 4 calories per gram. Fats are loaded with 9 calories per gram.

FYI Drinking alcohol has 7 calories per gram but is not included here as part of nutrition.

What is Protein?

amino acid

Students learned in the first MatchCard that protein is found in meats, poultry, eggs, nuts and beans. But what is protein used for?
  1. Can be an energy source instead of carbs
  2. Provides the structure, or skeleton, that makes up the cells of our body
  3. Many hormones, enzymes, and other substances our body makes are made of proteins.

Check for Protein

You can buy Biuret Regeant Solution commercially to check for the presence of protein in different foods. You can get it on the internet or from science or chemistry supply stores for around ten dollars.

Put a variety of foods on the table, let the students guess if they would have high amounts, medium amounts or no protein. Let them check their guesses with the biuret solution.

Protein Rainbow Salad

protein recipe protein recipe

Mix these ingredients for a fun and easy protein dish. Salads are usually served cold but this can be heated.

Alphabet of Amino Acids

amino acid

Proteins are made out of amino acids. The drawing on the MatchCard shows the basic structure of an amino acid. The question mark shows where an “R” group could be attached. There are 22 different amino acids, each with a different group of atoms at this location on the molecule. Amino acid molecules bind to each other to make proteins. Just as 26 letters of the alphabet make up and endless number of words, the 22 different amino acids join in different patterns to create an infinite number of different proteins.

Protein Matrix

gelatin experiment gelatin experiment
Add 2 tsp of water to gelatin, stir, then knead. A ball of protein will result.

Protein forms the cytoskeleton or inner matrix of cells that gives it its shape. This activity will demonstrate the protein matrix. Empty one envelope of unflavored gelatin into a small container. Add two teaspoons for water and mix in quickly. Knead the mixture with your hands. Let it set a few minutes and feel the texture again. Compare it to the texture of the cartilage in your ear which is made of collagen which is a protein. You can also have a flavored gelatin snack which is high in - you guessed it - protein.

Protein and Fat Models

If you did made the marshmallow model of carbohydrates, add a new color to stand for nitrogen and make an amino acid molecule.

If you used the coins, let the nitrogen be represented by a nickle. Also make a fatty acid chain. The student should recognize that carbs, protein, and fat are made out of largely the same atoms. That is why our body can easily convert the extra calories we consume into fat.

In the same way, if a person is dieting or starving, the body will break down the fat stores, convert them into glucose, and the cell can use that for energy.

amino acid marshmallow
Make 3 amino acids with the materials from your carbohydrate molecule and the 3 nitrogen molecules.

What Are Fatty Acids?

fatty acid molecule

Like carbohydrates and proteins, we can get energy from fats - 9 calories per gram in fact. Fats form important substances inside the body, including cell membranes and other parts of the cell.

Fatty acids are made of carbon chains of differing lengths. They are considered saturated if all of the carbon atoms are saturated with hydrogen atoms. Unsaturated fats do not have all of their carbon atoms saturated by bonding to hydrogen atoms. Unsaturated fats are healthier for your heart.

fat marshmallow
Make a fatty acid chain.

Butter. Margarine. Butter.

margarine butter experiment margarine butter experiment margarine butter experiment

Discuss that butter is an animal product made from cream. Margarine is a vegetable product made from corn oil. Which is unsaturated? (Answer: Margarine)

Fat is Flavor

The properties of fat help to give food flavor. Try eating cooked noodles with and without butter or margarine. Which tastes better?

Sprinkle both with parmesan cheese. Do you taste the cheese better with or without the butter?

Keep in mind how many extra calories are in fat. Think of how much fat you want to add to your diet in order to temporarily please your taste buds.

Hydrophobic Fat: Avoids Water

Activity: Try Mixing Fats and Water

Water and fats do not mix well. Try it. In a tall, thin container add some cooking oil. Add water that has been dyed blue or any other color. Watch how they separate from each other.

Notice how many salad dressings have their oil and water mixtures separated and need to be mixed by shaking. They won’t stay together too long.

Why? Water molecules are polar with slight charge - almost like a magnet - one side is positive and one is negative. Substances that mix easily with water usually have a charge as well. Fats do not have a charge, hence will not mix.

Fun With Food Dye

Here’s a fun experiment. Pour milk into a wide container like a pie dish. Gently add drops of different food coloring to the milk. Try not to disturb the surface. Now, add a single drop of dish soap to the milk. The colors will begin to swirl as the hydrophobic (water hating/fat loving) end of the soap molecules bind to the fat molecules in milk. When the reaction ends, add another drop to the dish again and the reaction continues.

Try with different types of milk: whole milk, cream, fat free milk. You can write a hypothesis about how the amount of fat in the different types of milk will affect the food dye and create a science experiment.

Soap, Water, and Fat

Soap is a unique substance. One part of its molecules have a charge, so it is considered hydrophilic (water loving.) The other part of a soap molecule does not have a charge and is water hating (hydrophobic) and fat loving.

Do you see how dish soap cleans your plate after a greasy meal? A molecule of soap attaches to a molecule of fat. The other end of the soap molecule attaches to the water and sweeps the grease away. Try washing a greasy plate with and without dishsoap.

MatchCard Science

How To Use MatchCards


MatchCards make science concepts and corresponding vocabulary interactive. As students move the information pieces on the MatchCards they review the material they have already learned.

Download the FREE MatchCard Science Instructor's Guide and see how MatchCards can make building their science knowledge base fun.

Nutrition, Health, and Safety Unit Study

Nutrition, Health, and Safety Unit Study Cover

Promote healthy choices for optimal living with 11 objectives.

See more about the Nutrition, Health, and Safety Unit Study.

12 Science Unit Studies

MatchCard Science Cover

Chemistry is only one of twelve complete unit studies for kids in 3rd to 8th grade.

Comprehensive objectives, hands-on projects, suggested science fair experiments, and the fun game-like MatchCards keep them interested in learning science. See all twelve MatchCard Science Unit Studies.

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