Case Lesson 13 Beans, beans are good for your heart.

Why? Beans are high in fiber. Fiber is good for digestion. Fiber reduces cholesterol. Cholesterol is bad for the heart. So. Beans are good for your heart. Who likes beans?

Servette HC

Ice Hockey Who would like to go and watch Ice Hockey? How many people in this school would like to go and watch the Servettee Ice Hockey Team? How would you find out? Discuss and decide.

A Fair Sample? How many people would you need to ask? Who would you ask? Where would you ask?

Why? Why do you need to ask so many people? How do you know your sample is accurate? Discuss and decide.

Biological Samples Broad bean seeds

How do the bean seeds vary in appearance? Have a look at a few broad beans to see how they can differ. Can your give two differences that occur between beans?

Broad bean seeds How many beans do you need to have in a sample so that all the beans in the “population” are represented?

The “Lucky Dip” Principle If every group has a sample of TEN seeds to look at …… how can you give every bean in the container an equal chance of being picked? That you have a fair sample.

Activity 1: Bean Variables You have been given ten bean seeds from a jar. The ten seeds were chosen at random. Look carefully at the beans. Write down at least two things that are the same in all the seeds you have been given. Write down at least one way in which the seeds differ from each other. The ten seeds you have been given differ in size. Use the bean measurer to divide them into two groups, large and small.

How many beans do you have in each group? Number of large beans: _____ Number of small beans: _____ Compare your results with other groups. Did everyone find small and large seeds in their samples of ten?

Now record in this table the number of large and small beans, which each group found in their sample of 10 beans. Copy the results into your book on the next page and onto the slide. Did everyone find small and large seeds in their sample of ten?

Name of groupLargeSmall 1 Snakes 2 Frogs 3 Eagles 4 Spiders 5 Sharks 6 Tigers Question 5Activity 2

Activity 2: A sample of beans Put your group’s ten beans into a bag. Shake the bag to mix up the beans. Take two beans from the bag without looking. In the first line of the table, write how many large, and how many small beans there were in your sample of two. Put the beans back in the bag, shake it, and take another two beans out. Repeat the process ten times in all. Complete the table with the number of small and number of large beans taken each time.

SampleNumber of beans that are Large Small

1. How many times did your sample of two contain no large seeds? 2. How many times did your sample of two contain no small seeds? 3. If you only take two seeds at a time from the bag (without looking) could you miss finding one of the two sizes of beans? Explain how you know this.

The sample Suppose there were some differences in the seeds you could not see? 4. If you picked just two, could you miss some of the differences?

Use the data from the class results. 5. Did everyone find both large and small beans in their sample? 6. If there are some differences in the beans that we cannot see, do you think that if we take a sample of ten we will find some of each kind? Link to class results.

7. How many large beans were there in the sample containing most large beans? 8. How many large beans were there in the sample containing fewest large beans?

9. So if you take a sample of ten instead of counting every bean in the bag, how accurate do you think your guess would be about how many of each size there were in the bag?

Activity 3 Growing Beans Each group selects a bean to grow. Complete the label with the group’s names and whether you chose a large or small bean. Do not take the label off its paper. Put the label and the beans inside the envelope so they can be planted for you.

Activity 3 Growing Beans Do you think the size of the bean seed will affect the size of the shoot that grows when the seed germinates?

Activity 3 Growing Beans Why do you think it is a good idea to ask Jean-Paul to plant the beans for you? What must we do to ensure that all the beans have a fair chance of growing?

Wash your hands.

Opinion Polls A recent opinion poll carried out by the student council said:- 60% of students at La Chat prefer 40 minute lessons compared to 45 minute lessons. How many students would you need to ask to make it a good survey?

Key Words 1.Probability 2.Sample 3.Representative