HotPopRobot

Arushi Nath, Grade 5 Student, Toronto, Canada

do your :bit is a global micro:bit challenge for children and teens to combine creativity and technology to come up with solutions for the United Nations Global Goals. In particular, the challenge focused on UN Development Global Goals 14 (Life below Water) and 15 (Life on Land) and encouraged kids to come up with innovative ways to use micro:bit to help protect life on land and below water. The Challenge received over 1000 entries.

My project MY SCALE to measure the quality of water in Lake Ontario is the North America Runners Up of the Micro:bit Challenge. The project was selected from among over a 1000 entries. (see pdf version)

Here is my story!

I am Arushi. I am a Grade 5 student from Toronto, Canada. I love space, music, coding, and building robots.

I stay near Lake Ontario. I often bicycle around the lake. Sometimes I go sailing and canoeing during summers. Last summer, I saw signs posted around Lake Ontario Waterfront saying that water is not safe for swimming due to high levels of sewage discharge and bacteria. I also saw signs showing pictures of fishes from the Ontario lake that are safe to eat. I was puzzled.

Problem:

It seems that water in Lake Ontario is bad for swimming but not bad for the fishes. Why is that?

I am a Maker. I love making projects using things I can find in my home, from old toys, old electronics, or from the local dollar store. In the past, I have made some submarine related projects that could go underwater, take videos, and collect information about the temperature of water and change in light.

So I thought, can I make a simpler device that will allow me to measure water quality. I could then take water quality readings from Lake Ontario and see how safe the water is for fishes and humans.

I searched online to see how water quality readings are measured. I came across many methods. Some were very complicated or required advanced sensors. But I wanted to use a micro:bit for my project.

I drew my inspiration from the Appalachian Citizens Enforcement Project website where they talked about water conductivity. Conductivity is not a pollutant itself but serves as an indicator of the presence of pollutants. Thus saline or polluted waters are more conductive than clean water.

My Idea:

I came up with a project: MY SCALE” or (M)icro:bit for (Y)ouths: (S)alinity and (C)onductivity (A)nalysis in (L)ake (E)nvironment based on the instrument I first imagined and drew on paper.

My SCALE measures how easily current can pass through water. If the water is clean, then very little current would pass through. As the water becomes dirtier and polluted from sewage and rain water flowing into the lake from the city, more current should pass through it. And polluted water is not good for fishes, turtles, water birds and other living things found in the lake.

Making of MY SCALE:

MY SCALE is made from things found in any schoolkid pencil case: 2 pencils, 1 eraser, and 1 sharpener. In addition, you need 2 wires attached to alligator clips or metal clothespin. I sharpened the 2 pencils on both the ends and taped them to one side of the Micro:bit. The pencils were separated by a piece of an eraser. I then attached the 2 wires to the sharpened end of each pencil using alligator clips. The other end of the wires went to Ground pin and Pin 0 of the Micro:bit.

I then wrote and uploaded a small code to measure and display conductivity between the 2 ends of pencils used LED display of the Microbit. MY SCALE is ready!

I simply need to dip the sharpened ends of the pencils into water and readings are displayed on the Micro:bit. The higher the readings, the lower the conductivity of the water, and the higher the water quality.

THE CODE

Here is the print screen of the simple code I made.

How does MY SCALE work?
I tested my device on different water types. I found the readings of tap water from my home to be 596, readings of a glass of water with 2 teaspoons of salt to be 104, and readings from the Ontario Lake water to be 364.

Conclusion:

This meant that Ontario Lake water did not have as many impurities as saline water (with 2 teaspoons of salt in a glass of water) as that would be bad for freshwater fishes. But the water quality is not as good as tap water used for bathing. This explains why Lake Ontario is okay for fishes but not good for swimming.

I was happy as I was able to find answers to my questions by creating my own experiment.

Future Plans:
If more kids make this device, I can create a crowdsourced map to show water quality information at different locations. It could help us find locations where sewage is entering Lake Ontario and polluting it. This device could be used by kids and adults anywhere in the world to find the source of water pollution and test water quality levels for fishes.