### Doggie data

**Directions for teachers:**

Ask students to use the interactive graph “Median life spans of purebred U.K. dog breeds” from *Science News* article “Explore the expected life spans of different dog breeds” and answer the set of questions below. Use this as a quick data- and design-focused activity in your classroom. The extension connects to the *Science News* article “Calculating a dog’s age in human years is harder than you think.” For a lesson plan tied to that article, check out “Mathematical models of a dog’s age.” Consider having more advanced students propose a study to create similar graphs for dog breeds other than Labrador retrievers. To learn more about the data set and calculations, students can go to the primary research paper linked at the bottom of the *Science News* article.

**Directions for students:**

Use the interactive graph “Median life spans of purebred U.K. dog breeds” from the *Science News* article “Explore the expected life spans of different dog breeds” and answer the set of questions below as directed by your teacher.

**A dog’s life span**

1. Look at the interactive graph. Using the search bar, choose five dog breeds and add them to the graph. Are there any patterns that you notice? Which breed has the longest median life span? Which has the shortest? Compare your answers with a partner.

*Student answers will vary.*

2. For the dog breeds you’re familiar with, are there any physical characteristics that are similar among the longest living dogs? What about the shortest living dogs? Why do you think these characteristics might make a difference? Do your observations align with what the scientists observed about how body and head size might influence canine life span?

*Student answers may vary based on the dogs they have picked. The longest living dogs are small and have long noses. The shortest living dogs are medium sized and have flat noses. Researchers in the article made a similar observation. This could be because dogs with flat noses may have more trouble breathing, which can lead to other health issues.*

3. What is the percent difference between the median life span of a miniature dachshund and a bulldog?

*The percent difference is 35%. The median life span of a miniature dachshund is 14 years, and for a bulldog it is 9.8 years. The difference between these values is 4.2 years. The average life span of the two breeds is 11.9 years. The ratio of the difference and the average is 4.2/11.9, or 0.35. Once you multiply by 100, you get 35%. This means that the median life span of miniature dachshunds is 35% longer than bulldogs.*

4. What is the median age of a species? And why do you think researchers used median age values as opposed to other calculations, such as mean or mode values? Where could you find additional information about where and how the scientists manipulated their data for the study?

*The median is** the middle value in a list of numbers arranged in increasing order, and the median age is the middle value when the life spans of all individuals of a breed in the data set have been arranged in increasing order.* *Maybe scientists used median values because they better represented typical life spans of a breed, as outlying values, such as premature dog deaths, wouldn’t impact median values as much as mean averages. To learn more about the data set and calculations, click on the **primary research paper** linked at the bottom of the *Science News* article.*

5. Name some limitations of the study. What would make the study better? What are some questions you have?

*The output data focused on purebred dogs and only used data from the U.K. Another study that collects data on dogs in other countries could reveal whether the trends apply in other places. The *Science News* article didn’t mention any data on crossbred dogs, which would be interesting because many dogs aren’t purebred.*

**Extension**

Refer to the article “Calculating a dog’s age in human years is harder than you think.” How would the dog breed affect the equation? How might that change the “Dog days” graph? Explain what additional studies would be needed to find the relationship and graph how dog age translates to human years for other breeds.

*The equation was based on yellow Labrador retrievers, which have a life span of 12 years, according to the article. The equation was derived specifically for aging of Labrador retrievers based on biochemical changes in Labrador breed DNA. That equation determines the slope of the graph showing how the breed’s age compares with human age. Because breeds have different median life spans, it’s likely that the slope of the graph will generally become steeper if dogs live shorter lives than Labrador retrievers or less steep if they live longer lives. But individual studies for each breed’s DNA changes with aging would be needed to determine whether the slope is actually similar to that of Labrador retrievers.*