Counting Kids

Est. Class Sessions: 2–3

Developing the Lesson

Part 1: Introduce Counting Kids Survey

Read “Armadillo Families.” “Armadillo Families,” found in the Adventure Book, describes how Professor Robinson and his daughter Betty conduct research on armadillo families. Their research uncovers the fact that armadillos most often have four pups living in the family at one time, which leads Betty to wonder about the number of children in most human families. Explain to students that the professor and Betty are doing research about armadillo families in the Brazilian rain forest and show students where South America and Brazil are on a globe or world map. Use the following prompts to guide discussion about the story:

Students will need to complete the Counting Kids at Home Homework Master prior to Part 2 of the lesson. Try to allow enough time to complete all of Part 1, which includes assigning this homework and planning the lab, on the first day of instruction for this lesson.

Pages 3–4

Ask:

Why do you think Betty recorded the information on a data table? (The data table will help Betty organize the information she collects about armadillos.)

Point out the different columns and what Betty will record in each column.

Pages 5–6

Ask:

Professor Robinson says that armadillos look for food when it is dark. Armadillos are nocturnal animals. What do you think nocturnal means? (It means they come out or are active at night.)

Armadillos. The nine-banded armadillo and a few of its South American cousins are the only known mammals to consistently bear litters of four genetically identical pups. Occasionally, twins or triplets are born, but this is a result of embryos dying. Over the years, these multiple births have led scientists to use the armadillo in studies where identical subjects are necessary—most notably, the study of leprosy.

Page 7

Ask:

Why do you think Professor Robinson put a mark on the tree? (Professor Robinson marked a tree to indicate where he saw an armadillo burrow.)

Page 12

Ask:

What happened when the armadillo was startled?

Share with students that some nine-banded armadillos have a jump reflex that can vault them three feet into the air when they are startled.

Page 14

Ask:

What is the most common number of pups in an armadillo family? (The graph shows that four is the most common number of pups.)

Explain that armadillos consistently have quadruplets. See the Content Note for further information.

What is the total number of armadillo families they saw? How do you know? (They saw 25 armadillo families. The vertical axis is numbered by twos, so I added 2 + 4 + 19 = 25.)

Have students note how the vertical axis is numbered (by 2s) and how to read the number indicated by each bar on the graph.

Pages 18–20

Ask:

Why didn’t any of the armadillo families have more than four pups? (On the other pages, Professor Robinson said that armadillos usually have 4 pups at a time, but sometimes one or two die. He also said that they grow up fast and stay with their parents for only a year. That means the pups are all the same age and there are not more than four at one time with their parents.)
How are human families different from armadillo families? (Human families usually have one child at a time, while armadillo families usually have litters of four. Human families have different numbers of children at home for many years. The children are usually different ages because it takes many years for humans to grow up and leave home. Human families can be big with lots of children, while armadillo families usually have only
4 pups at home for only one year.)

Page 22

Ask:

What other facts did you learn about armadillos?
In addition to how many pups they normally have and how long it takes for the pups to grow up and leave home as previously discussed, students may say they learned what they eat, when they like to find food, what happens when they are startled, and where they live.
What do you think Betty will do when she gets back to her classroom? (We can guess that she will study the number of children in her classmates’ families.)

Discuss the Counting Kids at Home Survey.

Introduce the Counting Kids survey with the following prompt:

Do you think the number of children in the families of students in Betty’s class will be the same as the data collected about armadillo families? How about the children in the families of students in our class?

Organize students into small groups and ask them to discuss the number of children in a human family and make a prediction about the number of kids in a human family. Students should realize that most human families do not have quadruplets as armadillo families do and that human children stay with their families for longer periods of time. After groups have had a chance to discuss their predictions, gather predictions from each group and record them on chart paper. These predictions will be revisited at the end of the lesson.

Tell students that they are going to conduct a survey about the families of their classmates like the survey Betty and her father conducted on armadillos. Explain that a survey is an investigation made by collecting information (data) and then analyzing it.

Lead a class discussion about how students will conduct their survey of the class. Encourage them to use the Adventure Book story as a model.

Ask:

How did the Robinsons collect the data?

Guide them to express the idea that there will be different numbers of children in different families, and that they want to find out how many families have one child, how many have two, how many have three, and so on. Point out to students that Betty and her father went to each den to count the number of pups in each armadillo family.

Ask:

Can you think of an easier way to collect our family data?

Guide them to the idea that each student can collect his or her own family data. Students will fill in the Counting Kids at Home Homework Master in class and take the page home for verification from a parent.

As students list their family members on the data table, it is likely that questions will arise about who should be counted as children in the family. Students (and parents) may wonder, for example, if they should count children who live in their home who aren’t legally their siblings, siblings who live at home part of the time, or siblings who live somewhere else.

Such questions should be discussed and students should come to consensus about which children to include in the list. Explain to students that scientists face the same kinds of decisions in their research. If the class is having difficulty with these decisions, suggest that they collect data just as the Robinsons did in the Adventure Book, counting all the children who live in each home.

Draw a Picture.

Display a blank sheet of chart paper and ask:

What question does the survey help us answer? (Possible response: How many kids are in a typical human family?)
What variables are you comparing? (Possible response: number of kids and number of families)

Draw a picture to represent the variables in this investigation. The drawing should include a representation of more than one family, with the number of children emphasized in some way. See Figure 2.