Fat in Foods
This is a level 5 measurement strand activity from the Figure It Out series. It also has an achievement objective from the Level 5 Number strategies and knowledge substrand.
solve problems using ratios and units of mass
Practically any dietary issue is controversial. The role of fat in the diet is as controversial as any. You need to be careful about how discussion on this topic develops and what statements you make. In your class, you may have obese students and potential anorexics. You may have your own strongly held but controversial
theories on diet and nutrition; you should make sure that you don't teach these as fact. The overwhelming evidence is, however, that obesity is a major threat to our young people, and we need to ensure that they are aware of the importance of a healthy, balanced diet and lifestyle.
In question 1, the students learn how to compare the amount of fat in different foods by converting the given information into a standardised measurement: grams of food per gram of fat. This is a question of ratios, but in each case, the ratio is expressed in the form x : 1 for ease of comparison.
You should discuss with your students the approximate nature of the data in this activity. All measurements have been rounded to the nearest gram, and your students should do the same with the results of their calculations. In practice, the fat content of many of the items listed will vary considerably. You could suggest that your students do the calculations without a calculator. They should be able to do most of them easily in their heads.
Once they have completed their table, the students have to decide which types of food have the highest and lowest proportions of fat. They could structure the task by grouping all the given items into three categories: little or no fat, moderate fat, and high fat. You could also ask them to add 5 more items to each category, based on what they think the fat content of those items would be, and then to check that they have correctly assessed them.
In question 2, the students are asked to find the fat content of a muffin, based on the amount of butter used, and then to complete an equivalence task. The unit used in each case is the one that is most appropriate for that food. Again, it is expected that the answers will be very approximate, and the students should not need calculators to work them out.
Question 3 asks the students to make up some sample lists of foods that Jeremy could eat, keeping within the dietician's guidelines and using the information from page 4. They should soon see that combinations such as a hamburger and large fries contain the recommended daily maximum or very close to it.
For this investigation, the students need to collect nutritional information from the packaging of prepared foods and then collate and analyse it. The information panels use standard headings, so it is a simple matter to enter the information into a computer spreadsheet. Once the students have done this, they can experiment
with different kinds of graph until they find the best way of comparing the fat (and perhaps the carbohydrate and sodium) content of the various foods. They should consider:
- graphs that display a single piece of information (for example, total fat content per 100 grams) for 20 different foods
- separate graphs for each of 20 foods, each displaying multiple information.
Despite the wide variety of graph types available with computer spreadsheets, bar graphs are still one of the most suitable types of graph in this situation.
The students could create a wall display using their data and graphs. When preparing displays, they should include the conclusions they have reached from their investigations. Some may even decide to make changes to their own eating habits as a result!
This activity could form part of a much larger unit on healthy eating.
The National Heart FoundationÕs website has information about fat and carbohydrates in foods (see www.nhf.org.nz ). The Foundation's Fat Kit, which is suitable for school use, is a useful resource for demonstrating the type and amount of fat in commonly eaten takeaways. Included in the kit are teaching notes on healthy takeaway meals and alternatives to commercial takeaway choices. It is sometimes alleged that fast food franchises are secretive about the content of their foods, but students will find that they have very detailed nutritional information on their websites, for example:
- investigate how knowledge of science and technology is used by people in their everyday life (Making Sense of the Nature of Science and its Relationship to Technology, level 5)
Health and Physical Education
- access and use information to make and action safe choices in a range of contexts (Personal Health and Physical Development, level 4)
Answers to Activity
Note that all numbers and answers in this activity are approximate.
1. a. (and 2b)
b. Meat, dairy, and fried products tend to be high in fat content because animals produce and store fat.
c. Vegetables and fruit
2. a. 7 g. (100 ÷ 12 x 0.8 = 6.67)
b. See table under 1a, above.
3. Answers will vary.
Answers will vary.