National Agricultural Literacy Curriculum Matrix
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Lactose Lab: Some Don't Like it Sweet
9 - 12
In this lesson students will learn the chemistry and composition of milk, identify the difference between a monosaccharide and disaccharide, and carry out a laboratory activity testing the effect of the enzyme lactase on various milks.
- Chemistry and Composition of Milk PowerPoint
- Computer and LCD projector
- Ice cube tray (1 per group)
- You could also use a muffin tin or 8 disposable condiment containers.
- Glucose test strips (8 strips per group of students)
- These can be obtained through a local pharmacy or online distributor. These test strips are used by diabetics to measure glucose levels in urine. Be sure to choose the test strips which change color and measure a glucose level, not just simply the presence or absence of glucose. Keto-Diastix Reagent strips is an example of a brand that works.
- Lactaid tablets (1 tablet per group)
- 100 ml of hot water in a cup or beaker (per group)
- Milk Samples:
- Cow's milk
- Goat's milk
- Lactaid milk (cow's milk that is lactose free)
- Soy milk
Essential Files (maps, charts, pictures, or documents)
lactase: an enzyme produced by the large intestine which breaks down lactose
enzyme: a substance that acts as a catalyst to bring about a specific biochemical reaction
disaccharide: a class of sugar whose molecules contain two monosaccharides
monosaccharide: a class of sugar whose molecules contain a single saccharide
lactose: a disaccharide sugar present in milk which contains glucose and galactose units.
Background Agricultural Connections
Interest Approach – Engagement
- Introduce the lesson and assess your student's prior knowledge by asking them the questions below. Questions can be asked in a simple question and answer format with your entire class or you may vary your instruction by dividing the class into groups. Print the questions and give each group a single question and a short amount of time to research the answer. For your reference, the answers can be found in the "Background Agricultural Connections" section of this lesson plan.
- "Where does milk come from? When do animals begin producing milk?"
- "After milk is produced on a farm, it is sent to a processing plant to prepare it to be sold. What takes place at the milk processing plant?"
- "What nutritional benefits do milk and other dairy products such as cheese and yogurt provide?"
- "What is the name of the carbohydrate found in milk?"
- "What is lactose intolerance and how can it be managed so people can still consume dairy products?"
- After discussing these questions, inform your students that they will:
- review basic facts about the nutritional benefits of milk and dairy products;
- learn about the physical and chemical properties of milk as it relates to monosaccharides, disaccharides and enzymes;
- perform a laboratory experiment to determine levels of glucose found in various milk samples; and
- identify how milk processing methods can provide digestible milk for individuals with lactose intolerance.
Activity 1: Chemistry and Composition of Milk
- Open the "Chemistry and Composition of Milk" PowerPoint. Provide a method for your students to answer multiple choice questions. Options include:
- Use a classroom response or "clicker" system if you have one.
- If mobile devices, tablets, or iPads are available, use a free app or website to allow your students to answer each question. Poll Everywhere and Socrative are examples, but many programs exist.
- If digital devices are not available or time does not permit, have students answer using hand signals. A=hold up 1 finger, B= hold up 2 fingers, C=hold up 3 fingers, D=hold up 4 fingers, E=hold up 5 fingers.
- Use slides 2-4 to establish some basic facts about milk. Use the questions to help students understand that all female mammals produce milk after giving birth and that in the United States cattle provide the majority of our milk supply. Though all mammals can produce milk, cows produce the most milk when you consider the cost to produce each gallon (labor, feed, housing, healthcare, etc.).
- Using slide 5, ask your students, "What is milk?" We have established that the milk in our food supply typically comes from cows. Your students know it is white and they pour it on their cereal in the morning, but what is it? Explain to your students that milk contains water, lactose, fat, protein, and minerals.
- Use Slide #6 to review the nutritional benefits of consuming milk and dairy products.
- Use slide #7 to break down the typical percentages of each milk component. These percentages represent cow's milk. Milk from other species will vary in it's content. For example, goat milk has less lactose than cow's milk.
- Using slides 8-11 teach or review basic chemistry principles about enzymes, monosaccharides, disaccharides, and lactose. Use the same formative assessment method used in step 1.
- Using slides 12-14, teach students about lactose and it's enzyme, lactase.
- Summarize and apply what students have learned by teaching them about lactose intolerance. Use the information found in the "Background Agricultural Connections" section to prepare them for the next laboratory activity.
Activity 2: Lactose Lab
- To introduce the lab, show your students a commercial for lactose-free milk. Ask your students to use what they now know about enzymes, lactose, and lactase to guess how milk can be made lactose-free.
- Divide students into lab groups.
- Provide the laboratory supplies for each group and 1 copy of the Lactose Lab handout to each student.
- Give students adequate time to complete the laboratory procedures and answer the questions on their handout.
- Once students have completed the laboratory activity, return to your question from step 1. How can milk be processed so that it is lactose-free? Have students use what they have learned in this lesson to answer the question.
After conducting these activities, review and summarize the following key concepts:
- Milk and milk products provide important nutrition to our diet.
- Milk contains the disaccharide, lactose.
- Food production systems are influenced by consumer's choices. As lactose intolerance has become more prevalent, the agriculture and food processing industries use science to find solutions such as lactose free milk.
Have students compare the nutrition labels for cow's milk and other plant-based milk substitutes such as rice milk, soy milk, and almond milk. Have students write a summary comparing the differences. What are the similarities and differences? Are the vitamins and minerals listed on the nutrition label contained naturally or were they fortified?
Suggested Companion Resources
- Bringing Biotechnology to Life (Activity)
- Brittlelactica: Planet in Need (Multimedia)
- Consider the Source- Cheese (Multimedia)
- Dairy in the Mountain West: Our Family of Farmers (Multimedia)
- Everything is Chemical (Multimedia)
- Food Chemistry Experiments (Teacher Reference)
- The American Dairy Industry (Website)
Agricultural Literacy Outcomes
Science, Technology, Engineering & Math
- Identify current and emerging scientific discoveries and technologies and their possible use in agriculture (e.g., biotechnology, bio-chemical, mechanical, etc.) (T4.9-12.e)
- Provide examples of how processing adds value to agricultural goods and fosters economic growth both locally and globally (T4.9-12.g)
Food, Health, and Lifestyle
- Explain how food production systems are influenced by consumer choices (T3.9-12.f)
Common Core Connections
Speaking and Listening: Anchor Standards
CCSS.ELA-LITERACY.CCRA.SL.1Prepare for and participate effectively in a range of conversations and collaborations with diverse partners, building on others’ ideas and expressing their own clearly and persuasively.
Language: Anchor Standards
CCSS.ELA-LITERACY.CCRA.L.4Determine or clarify the meaning of unknown and multiple-meaning words and phrases by using context clues, analyzing meaningful word parts, and consulting general and specialized reference materials, as appropriate.
Mathematics: Practice Standards
CCSS.MATH.PRACTICE.MP4Model with mathematics. Students can apply the mathematics they know to solve problems arising in everyday life, society, and the workplace. Students who can apply what they know are comfortable making assumptions and approximations to simplify a complicated situation, realizing that these may need revision later. They are able to identify important quantities in a practical situation and map their relationships using such tools as diagrams, two-way tables, graphs, flowcharts and formulas. They can analyze those relationships mathematically to draw conclusions.
Food Products and Processing Systems Career Pathway
FPP.02.01Apply principles of nutrition and biology to develop food products that provide a safe, wholesome and nutritious food supply for local and global food systems.
FPP.02.02Apply principles of microbiology and chemistry to develop food products to provide a safe, wholesome and nutritious food supply for local and global food systems.
Health Standard 5: Demonstrate the ability to use decision-making skills to enhance health.
5.12.1Examine barriers that can hinder healthy decision making.
Health Standard 7: Demonstrate the ability to practice health-enhancing behaviors and avoid or reduce health risks.
7.12.3Demonstrate a variety of behaviors to avoid or reduce health risks to self and others.
HS-LS1 From Molecules to Organisms: Structures and Processes
HS-LS1-6Construct and revise an explanation based on evidence for how carbon, hydrogen, and oxygen from sugar molecules may combine with other elements to form amino acids and/or other large carbon-based molecules.