Ask your students how much milk they’ve had in the past 24 hours. I predict the amounts will be dismally low.

The Office of Dietary Supplements, National Institutes of Health, reports in its Dietary Supplement Fact Sheet: Calcium:

The National Health and Nutrition Examination Survey 1999-2000 found that average calcium intakes were 1,081 and 793 mg/day for boys and girls ages 12-19 years, respectively; 1,025 and 797 mg/day for men and women 20-39 years; and 797 and 660 mg/day for men and women ≥60 years. Overall, females are less likely than males to get recommended intakes of calcium from food.

It’s apparently not hip to drink milk. Though most students would agree milk is a healthy choice, they may believe it also holds risks because of additives or processing. They may believe they can get their calcium just as easily from other sources. However, some studies suggest that calcium supplements don’t confer the same benefits as calcium delivered via low-fat dairy products. Among examples cited in a Wall Street Journal online article is a low-fat diet containing three servings of diary, such as milk or yogurt, that contributed to greater fat loss around the waist than diets of equal caloric intake per day lacking the dairy regiment. Causes for the observation are not known but are suspected to lie in the combination of enzymes present.

Ask your students if they know why at least three servings of low-fat milk are recommended daily. What does the body use it for? Most students will be able to mention bone and teeth composition. Probably few realize milk is required for muscle contraction, both voluntary and involuntary, for hormone and enzyme secretion, and for neurotransmitter success. Emerging research suggests other benefits as well.

ScienceDaily  recently published a story called Longer Life For Milk Drinkers, Study Suggests. A study out of Great Britain “aimed to establish whether the health benefits of drinking milk outweigh any dangers that lie in its consumption. . . . The review brought together published evidence from 324 studies of milk consumption as predictors of coronary heart disease (CHD), stroke, and diabetes.” The researchers offered this conclusion:

Our findings clearly show that when the numbers of deaths from CHD, stroke and colorectal cancer were taken into account, there is strong evidence of an overall reduction in the risk of dying from these chronic diseases due to milk consumption. We certainly found no evidence that drinking milk might increase the risk of developing any condition, with the exception of prostate cancer. (Emphasis added)

How to Turn This News Event into an Inquiry-Based, Standards-Related Science Lesson

The following lesson could be integrated into a skeletal system unit, a nutrition unit, or a science literacy unit. After orally surveying students for how much milk they recently consumed and what they believe are the pros and cons to drinking milk, have them write down a prediction regarding how much calcium is recommended daily for a person their age. Have them express that quantity in metric units of mass. This may require some support from you, such as reminding them what the base unit of mass measure is (gram) and the various prefixes. Allow the students to decide which prefix is most appropriate. Then have them write down a list of the benefits and the negatives of consuming milk. This initial list will be revisited and appropriately revised later.

Show students the document from the National Institutes of Health quoted above, Dietary Supplement Fact Sheet: Calcium, or have them peruse it in pairs while in a computer lab.

Each student should answer these questions:

1. How much calcium is recommended per day for a person your age? (1,300 mg)

2. List the sources of calcium that you would/could/do use.

3. What does DV stand for? Why is the given DV not directly useful to you? (Daily Value. It’s based on a 1,000 mg Recommended Dietary Allowance, or RDA)

4. Should you adjust the given DV up or down? (Down)

5. List two forms of calcium in supplements. Which do you think is the better choice for you and why?

After this point, you could assign pairs of students to sections of the document and ask them to develop one or two essential questions for each section. After the students finish reading their assigned section and constructing answers to their essential questions, they should be encouraged to find one reputable resource that either confirms or discounts the fact sheet’s statements.

Finally, the student pairs should share their findings with the rest of the class. They could create posters for a “gallery-hop” where students walk around the room, from poster to poster, as the poster creators briefly describe what they learned, using their poster as a visual aid. In this way they reinforce concepts of collaboration and communication in science.

As a means of accountability, each pair of students might be required to construct two questions, either multiple choice or fill-in, that all students will be able to respond to correctly after hearing the pair’s presentation. You can use one of the two questions from each group for a class quiz. Part of that quiz should include a student reflection in which students describe how accurate their initial predictions were and the ways they have modified their conceptions of calcium and human nutrition. They should also reflect on how they may modify their lifestyle as a result of this lesson, and why.

Here are additional resources from the National Science Digital Library Middle School Portal: Eastsmart.org; Smart-Mouth.org; and Health Rules: Fitness and Nutrition for Kids. One other lesson idea is found at  Eating a Nutritious Lunch.

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