The World Fertility Rate: A Relevant Mathematics Topic

I have decided to begin to blog again. As someone who is very task oriented, I was always excited to be able to check of "write blog" from my To Do list, especially in the days when I blogged each day for one full school year. I really have no idea how I found time to do that. It must be that I created a 25-hour day. As of September of 2024, I am no longer in the classroom and I wondered what topics would be in my future blogs. You'll need to read future blogs to find out! 

Besides the near daily question of "Did I miss anything?" from students returning from an absence, the second most asked question high school math teachers hear is "When will I ever use this?" This is often heard for the first time in Algebra classes, where math begins to seem like an exercise in algebraic origami. For those of us that have an innate love of math, (I wore a red t-shirt that boldly declared “I Love Math” when meeting my colleagues for the first time at Champlain Valley Union High School in Vermont.) we don’t see the need for all math to be relevant. Math is beautiful and should be studied to improve reasoning and thinking. But sadly, it seems as if much of the United States feels that math must be relevant to be worthy of being a part of the curriculum.

And this leads me to the topic of today's blog - The World Fertility Rate: A Relevant Mathematics Topic. As I was looking at a daily news email a few days ago, I clicked on a link with the following headline:

Charting global fertility rates, which have declined by half since 1965

I won’t go into the all the details of what I discovered and ruin the fun for you. But I did find the following two graphs to be quite interesting and learned that the “Global Replacement Fertility Rate” of 2.3 children was reached in 2015. This is the fertility rate at which the population says constant. You might be wondering why it isn’t 2, but that is because we need to take into account the deaths of the female population before the end of their childbearing years. 

If I was using these graphs in my classroom, I would give students 5 minutes to look at both and write down what they notice and wonder about the graphs. Then, I would have them share their ideas with a partner for about 5 minutes. Next, we would debrief as a class for about 10-15 minutes. From our list of wondering questions, students would be asked to choose 1 or 2 of the questions and work in groups to try to find the answer to those questions. 

Possible questions could include the following: 

1. Why is China’s fertility rate lower than the fertility rate in the US now than before 1980?
2. If this trend were to continue, when would a global average fertility rate of 2.3 be reached?
3. Do countries with higher (or lower) fertility rates have common characteristics?

  

The data, graphs and analysis can be found at https://ourworldindata.org/global-decline-fertility-rate.

If you use this graph with your students, post how things went in the comments. Math educators sharing and learning from each other makes the world brighter.