### Old dog, new math

This exercise is a part of Educator Guide: Calculating a Dog’s Age Requires a Bit More Math / View Guide

Directions for teachers: After your students read the online Science News article “Calculating a dog’s age in human years is harder than you think,” ask them to answer the following questions. A version of the story, “Calculating a dog’s age requires a bit more math,” can be found in the August 15, 2020 issue of Science News.

1. The Science News article expresses two mathematical formulas in words. What are the formulas used to find?

The formulas are used to find a dog’s age in equivalent human years.

2. Write the formulas as equations in terms of x and y.

The formulas are y = 7x and y = 16(ln(x)) + 31.

3. Which formula do scientists claim is better? What evidence do the scientists give to support their claim?

Scientists consider the formula 16(ln(x)) + 31 = y to be more accurate because it is based on a biological comparison between dogs and humans. It takes into account that the relationship between dog and human ages can change over time.

4. Name one limitation of the research presented in the article. What other data would you want to collect to better support the claim?

The study only looked at Labrador retrievers. That means the formula y = 16(ln(x)) + 31 applies only to Labs. Researchers will have to repeat the study with other breeds to get age conversion formulas for those breeds. Additional data from different dog species should be collected to further support the scientists’ claim.

5. According to the article, what are methyl groups and what can scientists learn from them?

Methyl groups are chemical tags that get added and removed from DNA as animals get older. The changes are associated with growth stages. Scientists can compare changes across species and use the changes to track biological age.