Introduction
This is a kinesthetic math activity for students learning about the circumference, surface area, and volume of a sphere. Kinethetic learning is a method of learning that connects the position and movement of body parts with a concept or idea; i.e. learning through a physical activity.
For this activity, students "draw" a sphere with light using their arms and a camera set with a long shutter speed to take a photo of the sphere drawn. By having students stand in the same position and draw the sphere with their arms extended horizontally at their sides, it helps them to understand the correlation between diameter and the rest of a sphere. In this case, their two extended arms are the diameter of the sphere drawn. Once the sphere is drawn, students can measure their arm span to know the exact diameter of their sphere and are then able to calculate the circumference, surface area, and volume of the said sphere.
What is Shutter Speed and How Does it Work?
Shutter speed affects how long the shutter covering the lens of your camera will stay open when taking a picture and how much light will enter the lens. In other words, how long it takes the camera to capture and process a picture. With a short shutter speed, the picture will be taken quickly and will be darker as very little light was allowed to pass through to the lens. With a longer shutter speed, the picture will be taken slowly with a longer delay from pressing the button to capture the image to viewing the end result. A longer shutter speed allows for more light to pass through to the lens, and will result in a lighter, often almost completely white, picture.
Since a longer shutter speed allows for more light to pass through, it is preferable at night or in dark rooms. Creative photographers have taken advantage of this setting to "draw" with light in a dark area. Some examples:
This project works similarly to how these photos were taken. The next sections explain how to set up your camera or phone to have a long shutter speed, in what way students need to move the lights in order to successfully draw a sphere, and how to calculate the circumference, surface area, and volume of the sphere they drew using the length of their arm span.
How to Adjust the Shutter Speed on a Phone or Camera
Each model of phone and camera is different, so be sure to research what will work for you if the methods featured in the videos below are not applicable to you.
A Samsung Galaxy s10 is used in the phone setting video and a Nikon Coolpix Model# S9700 is used in the camera setting video. Most Android phones have a similar set-up as the s10, however Apple, Google, or the product of any other company may be different. In short, if you own or have access to a smart phone with a decent camera then it should allow you to adjust the shutter speed.