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Texas Farm Bureau

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FoodMASTER Middle: Weights and Measures

Grade Level
6 - 8
Purpose

Students will use common household measurement tools and scientific measurement tools and various methods of measurement to compare for accuracy. Students will also calculate percent error by comparing their measurements to actual values and apply these principles to analyze and decipher the components of a food as indicated on the Nutrition Facts label. Grades 6-8

Estimated Time
Two 60-minute activities plus optional homework assignment
Materials Needed

Interest Approach:

Lab 1:

Student Materials (Half of class will complete Assignment A while the other half completes Assignment B)

  • Assignment A, per group of 4-5 students
    • 1 and 1/2 cups all-purpose flour in a plastic bag
    • 1 set dry measuring cups
    • 1 scale (triple beam balance or kitchen scale)
    • 1-2 sheets wax paper
    • 1 strainer (wide mesh)
    • 1 medium bowl
    • 1 plastic knife
    • 1 plastic spoon
  • Assignment B:
    • 1-cup cooking oil in plastic cup (10 oz. or greater)
    • 1-cup water in plastic cup (10 oz. or greater)
    • 1 set dry measuring cups
    • 1 liquid measuring cup (1 cup measure or greater)
    • 1 graduated cylinder (100mL)
    • 1 scale (triple beam balance or kitchen scale)

Lab 2:

Student Materials per group of 4-5 students

  • 1 small cup of salt (represents sodium) 
  • 1 small cup of sugar (represents carbohydrates) 
  • 1 small cup of softened butter (represents saturated fat) 
  • 1 small cup of olive oil (represents unsaturated fat) 
  • 1 set of measuring spoons
  • 1 scale (e.g. triple beam balance)
  • 4 small empty cups
Vocabulary

accuracy: occurs when measurements are close to a quantity’s actual value

cups: a unit of volume that is most commonly used to measure most liquids, but can also measure dry ingredients

density: the mass of a substance per unit of volume

gram: a unit of weight equal to the mass of 1 cubic centimeter (cm3) of water at 4°C

mass: a measure of the amount of matter, or a measure of the force of gravity between two objects

matter: a material substance that makes up all physical objects and occupies space

meniscus: the curved upper surface of a column of liquid

precision: the quality, condition, or fact of being exact and accurate

volume: the amount of space an object occupies

Did You Know?
  • Farmers use weights and various forms of measurements in their daily work. Examples include measuring crop yields after harvest, calculating profits, or measuring feed rations.
  • Farmers use math every day from basic measurements and calculations of geometry, proportions, multiplication, and division to more advanced math used in calibrating machinery and irrigation pumps.
  • The old saying, "I wouldn't touch it with a 10 foot pole" came from the days before farmers had accurate measuring tools for building their barns. Farmers would use a 10 foot pole as a standard for measuring while building these structures.
Background Agricultural Connections

FoodMASTER (Food, Math and Science Teaching Enhancement Resource) is a compilation of programs aimed at using food as a tool to teach mathematics and science. For more information see the Background & Introduction to FoodMASTER. This lesson is one in a series of lessons designed for middle school science, food, and nutrition classes. Use the following links to see additional lessons in the series:

Weights & Measures        Fruits                  Milk                    Sugar                   Protein             
Food Safety Vegetables Cheese Fats & Oils Eggs
Energy Balance Grains Yogurt    


Being able to make accurate and precise measurements is a skill needed in daily life, as well as in the science lab. For example, bakers and chefs must know the most accurate way to measure each ingredient to make the best tasting product. Depending on the state of matter (solid or liquid) a different measurement tool may be needed. Using the tool properly also affects the accuracy and precision of the measurements made. In this chapter, students will explore the proper use of measurement tools and investigate measurements used on Nutrition Facts Labels. 

It is important to use the correct measurement tools when preparing food. Dry measurement cups measure volume and should be used to measure dry ingredients only. You should use these tools when a recipe calls for amounts of dry ingredients in cups, etc. If a recipe calls for dry ingredients by weight (e.g. ounces), you should use a scale to measure the ingredients. You should also make sure to follow instructions carefully because some items need to be sifted, spooned, packed, or dipped. Liquid measurement tools measure volume and should only be used when a recipe calls for liquids to be measured in cups, etc.

  • Spoon: Stir flour in a small bowl or bag with a spoon. Spoon flour gently into a dry measuring cup. Level with the flat edge of a plastic knife over wax paper. 
  • Dipped: Dip the dry measuring cup directly into the container of flour, filling it to overflowing with flour. Level with the flat edge of a plastic knife over wax paper. 
  • Sift: Pour the flour into a strainer. Sift onto wax paper by shaking the flour through the strainer. Spoon flour gently into a dry measuring cup. Level with the flat edge of a plastic knife over wax paper. 

Tip: View the “how to” video lab demonstration (Weights & Measures Lab I Demonstration Video) to see a visual demonstration of the described flour measurement methods.

Proper Measurement Methods for Liquids 

Set the measuring cup on a level surface before pouring the liquid into the container. Allow any foam or bubbles that form after pouring to settle. Read the liquid measurement at the lowest point of the meniscus (curved upper surface of the liquid). 

Conversions 

  • Milligrams (mg) to grams (g): 1g=1,000 mg (Example: 1,600 mg = 1.6 grams; move the decimal place three places to the left). 
  • Grams (g) to Kilograms (kg): 1kg=1,000 g (Example: 50 g = 0.05 kg; move the decimal place three places to the left) 

Precision and Accuracy of Measurements 

The accuracy of a measurement is how much that measurement differs from a known, true value. For example, if a “10g” brass mass from a standard set of masses is measured on a reliable scale and is found to be 10g, than the mass is accurate, but, if it is found to be 9.8g, it is not. Percent error can be calculated to determine the accuracy of a measurement. Precision is how reliable the measuring device is and how reproducible its measurements are. A 100-milliliter beaker is not as precise as a 100 milliliter graduated cylinder. One hundred milliliters measured in a beaker will vary slightly every time the beaker is used. The graduated cylinder has more graduations and will be more precise.

The Food and Drug Administration (FDA) regulates Food labels, also called Nutrition Facts labels. They were created to ensure consumers of safe products. Over time, they have evolved to provide consumers with measurement information about food. This information helps consumers make educated decisions related to health and wellness. Each label provides nutrient information for a serving size of that product. Serving sizes are not necessarily based on portion size, but rather a standardized amount of the product that can easily be divided into the whole. Most serving sizes are consistent with similar foods and are measured using household measurements. A serving size of milk, for example, is always measured by cup. All Nutrition Facts labels include calories, daily value, fat, cholesterol, sodium, carbohydrates, fiber, protein, certain vitamins and minerals, and an ingredients list. Percent daily value (%DV) is based on the total amount a person on a 2,000-calorie per day diet should consume. In 2016, the Nutrition Facts label was updated; updates include larger and bolded font for servings per container, updates to serving sizes, larger font for calories, updated daily values, change in nutrients required, added sugars now included, and a new footnote. This value is determined by dividing the amount in a serving of the product by the total amount recommended and multiplying it by 100 to express it as a percentage. The ingredients list includes all ingredients in the product listed from those of the greatest weight to those of the least weight. We should use Nutrition Facts labels to ensure we are consuming an adequate diet.

Engage
  1. Display a Nutrition Fact label for your class to see.
  2. Ask the following questions, "How are weights and measurements used in this Nutrition Fact label?" Use further guided questions if necessary for students to recognize and point out that each nutrient is measured in grams or milligrams.
  3. Ask students how these measurements are taken and how they can help us.
  4. Give each student one copy of the Everyday Weighing and Measuring student handout. Instruct students to complete the worksheet (in class or as homework) using a Nutrition Fact label of their choice. Students can find food labels in the grocery store, USDA’s FoodData Central, or use the labels provided in this lesson.
  5. If this activity is completed in-class, allow students to work in small groups on the lab sheet to further explore the topic and respond to questions.
  6. Follow-up with a class discussion about student findings related to their favorite snacks and student generated ideas for choosing healthy snacks.
Explore and Explain

Food Exploration Lab 1: Mastering Measurements

Teacher Preparation:

  1. Review information found in the Background Agricultural Connections section of the lesson, lesson Procedures, and the attached Essential Files.
  2. Prepare lab materials for each group:
    • Assign 3 groups to Assignment A and 3 groups to Assignment B.
    • Fill 1 plastic bag per group (assigned to Assignment A) with 1 and 1/2 cups of flour
    • Fill 2 plastic cups per group (assigned to Assignment B) with liquid ingredients (1 cup with water, 1 cup with cooking oil)
      • Note: If you have 6 student groups, 3 groups will use flour (Assignment A) and 3 groups will use liquids (Assignment B).  
  3. In the lab investigations, students will be measuring and massing ingredients, calculating percent error, and converting measurements. Consider reviewing with students how to tare a scale, how to properly measure dry and liquid ingredients, how to calculate percent error, and how to convert between common measurements (e.g. ounces to cups, cups to tablespoons).

Lab Procedures:

  1. Give each student one copy of the Mass Measurements student handout.
  2. Ask students to read pages 1-3 and complete the "Think About It" focus questions on page 4.
  3. Prepare students to begin the lab investigation by requiring students to wash their hands and emphasize the importance of practicing good food safety behaviors by not consuming substances used as part of the lab investigation.
  4. Distribute lab materials. It is recommended that materials are organized into stations for easier distribution. Students should be arranged in small groups of 4-5. Each group should receive the lab supplies outlined in the Materials section as well as 1 copy of the Mastering Measurements lab sheet.
  5. Launch the lab by asking students to make a prediction about accuracy of methods and precision of tools used when measuring ingredients. Show students the Weights & Measures Lab I Demonstration Video. Then give them time to complete their lab exploration following the instructions found on the Mastering Measurements lab sheet. Students should discover the following: 
    • Dry Ingredient (Flour): The most accurate method for measuring flour is the sifted method. In cooking, it is recommended that flour be sifted before measuring. Flour tends to be a more difficult ingredient to measure due to its tendency to pack down, which increases the density of the ingredient.
    • Liquid Ingredients (Cooking Oil & Water): The oil and liquid should weigh approximately the same regardless of the tool used to measure them; however, students will observe a difference in the accuracy of measurement. The liquid measuring cup should allow students to observe and measure the amount of liquid using the meniscus; however, that does not necessarily mean the measurement will be completely accurate. The dry measuring cup does not allow such accuracy when measuring liquids and is more prone to spilling (human error). Both of these common kitchen tools should prove to be the least accurate. Of the three tools, the graduated cylinder will be the most accurate. The graduated cylinder should have the most graduations allowing the observer to measure to the nearest milliliter. When comparing the two liquids, the relative density of cooking oil and water differ, resulting in different weights of each. Oil has a lower density compared to water, and therefore weighs less per unit volume.
  6. Once the lab is complete, allow students to work in small groups to complete their lab sheet to further explore the topic and respond to lab questions.
  7. Follow-up with a class discussion about the importance of accurate methods and tools in science. See Enriching Activities for ideas on how to further extend this lesson.
    • Optional: Explore accuracy further using different methods and measurement tools (e.g. beaker)

Food Exploration Lab 2: Label Logic

Teacher Preparation

  1. Review information found in the Background Agricultural Connections section of the lesson and the attached Essential Files.
  2. Prepare materials for each group by pre-labeling cups for each student group. Label each cup with an ingredient name (i.e. salt, sugar, butter, and olive oil). Each ingredient should have two labeled cups (one filled, one empty). Fill each cup approximately 1/4 full with salt, sugar, butter, and olive oil. 

Lab Procedures:

  1. Distribute lab materials. It is recommended that materials are organized into stations for easier distribution. Students should be arranged in small groups of 4-5. Each group should receive the lab supplies outlined in the Materials section as well as 1 copy of the Label Logic lab sheet.
  2. Prepare for lab by requiring students to wash their hands. Emphasize the importance of practicing good food safety behaviors by not consuming substances used as part of the lab investigation. Show students the Weights and Measures- Label Logic video to demonstrate the lab.
    • Note: Be sure students read Mass Measurements and completed the focus questions as outlined in Lab 1. 
  3. Launch the lab by asking students to begin following the instructions on their lab sheet. Students should conclude the following:  
    1. Snack #1 – Classic Potato Chips: Students should find the classic potato chips have more calories, fat, and sodium. 
    2. Snack #2 – Baked Potato Chips: Students should find the baked potato chips have fewer calories, grams of total fat, and sodium. The baked chips also contain more fiber. However, the baked chips do contain more sugar. Overall, due to the lower number of calories and fat grams and higher fiber content, baked chips are the better option.
  4. Allow students to work in small groups to complete the lab sheet and respond to lab questions.
  5. Follow-up with a class discussion about reading Nutrition Facts labels to obtain health information about food. See Enriching Activities for ideas on how to further extend this lesson.
    • Optional: Have students bring in labels of their favorite snacks to review as a class.
Elaborate

  •  Have students bring in labels of their favorite snacks to review as a class. 

  •  Explore accuracy further using different methods and measurement tools (e.g. beaker).

Evaluate

After conducting these activities, review and summarize the following key points:

  • Food labels are used to indicate the nutrition value of foods.
  • Accurate measurements and conversions are used to create accurate food labels.
Acknowledgements

This lesson was partnered with East Carolina University. The FoodMASTER program was supported by the Science Education Partnership Award (SEPA) which is funded from the National Center for Research Resources, a component of the National Institutes of Health.

  • Primary Authors:
    • Virginia Stage, PhD, RDN, LDN
    • Mary White
    • Ashley Roseno, MAEd, MS, RDN, LDN
    • Melani W. Duffrin, PhD, RDN, LDN
  • Graphic Design: Cara Cairns Design, LLC
Recommended Companion Resources
Author
FoodMASTER
Organization
FoodMASTER
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