I'm so very excited to give you this guest post from Sarah Richards. I saw a picture of her children doing this activity on instagram and asked her to do up a blog post to share here! It is such a great example of hands on, out door practical math. Plus she shares how she adjusts the activity for different ages. Enjoy...
Measuring and Estimating the Age of Trees
By Sarah Richards
I love Becky's hands on approach to math, and we really enjoy her units. I was so happy when she asked me to share this simple maths in nature activity that I have enjoyed doing with the children.
This week we headed to our local woods to observe the trees and estimate their age. The only preparation needed was to stash a tape measure, notebook and pencil in my bag. We were going to measure the girth or circumference of the tree's trunk, to estimate its age. Each year the girth of the tree increases as a new ring of growth is formed. I had read that although rates of growth may vary between different types of trees, on average they grow at a rate of 1 inch (2.5cm) per year.
Once out on our walk, I let the children select trees to measure. This was half the fun as they went off the path and sang "we're going on a tree hunt, we're going to find a big one, we're not scared." We then used the tape measure to measure the circumference of the tree's trunk and made a note of the measurement. We used our knowledge that 1 inch equals 1 year of growth and estimated the tree's age. We quickly found some that were too big to measure and guessed how much bigger they were* and therefore how old they might be.
I asked the children if they noticed any other differences in the younger and older trees. They observed that the older trees were taller, and that the bark on the older trees was rougher and was covered in interesting looking burls.
When we got home, I showed my four year old that the units on the tape measure were the same as those on a ruler. With the help of a ruler we drew a section of the tape measure, along with some of the trees she had seen, including the tall 'bumpy' one. I then wrote the word 'tree' for her to copy.
With my older children, I reminded them of the meaning of circumference. They also had a little extra work as they had noted the circumference in cm’s and then converted that into inches at home. I let my 7 year old do this by comparing the front and back of the tape measure. With my eldest son I spoke about the meaning of 'estimate' and 'average'.
We then looked up trees in our nature books to see what could find about their growth. Next I asked them to write their own account of what we had done in their nature books.
I hope you and your family enjoy getting out in nature and having a go yourself!
Sarah lives in the UK, and has been home educating 3 of her 4 children for the past 2 years. She is one of the Games for Good contributers. You can find her on instagram @richardsfamilyschoolhouse (I really recommend following along with her, so many great ideas! Xx Becky)
*Becky's note: you could mark with chalk the extent to the tape measure, measure the gap and sneak in some addition here too.