Big Idea
In this lesson, we will learn about Solar Water Disinfection (SODIS) as a low-cost way to clean water. We’ll explore how SODIS can help lift people out of poverty by reducing waterborne illnesses and the burden of unpaid work, leading to healthier and more productive communities.
Take Action
In the ‘Take Action’ section of this lesson, we’ll use a micro:bit and a plastic bottle of water to create our own SODIS timer!
We will use the micro:bit’s light sensor to detect sunlight. After 6 hours of light exposure, the LEDs will notify the community that the water is safe to drink!
Learning Goals
Students will…
- Explain why access to clean water is important
- Describe how people collect and clean water in countries with poor access
- List the steps of SODIS and explain how it changes on sunny or cloudy days
- Discuss the pros and cons of SODIS
- Create a SODIS timer that uses variables and nested conditionals to track how long water has been exposed to sunlight and notify users when it is safe to drink
Materials
Per 1-3 students:
- Climate Action Kit
- micro:bit
- Computer with access to Microsoft MakeCode
- Flashlight
Get to Know the Content
- Make sure you’ve completed our ‘Getting Started with the Climate Action Kit’ course
- Review the lesson
Big Idea (20 minutes)
Learn about SODIS and its impact on community wellness!
Take Action (45 minutes)
See how SODIS is saving lives in Kenya and build your own SODIS timer with the Climate Action Kit! The timer will track how long a water bottle has been in the sun and will notify the community once it is safe to drink.
We’ve provided 3 ways students may build the project to support scaffolding and differentiation in your classroom: ‘Use’, ‘Modify’, and ‘Create’.*
| Activity | Description |
|---|---|
| Use | Students will follow a step-by-step tutorial to build & use their SODIS timer. They will test how the timer works to track sunlight exposure. Success Criteria I can: – build a SODIS timer using the micro:bit – explain how the micro:bit detects light – explain how variables, conditional statements, and loops help track how long a water bottle has been in the sun Resources Tutorial Final Code |
| Modify | Students will follow a step-by-step tutorial to build their SODIS timer. Then, they will change the code to learn how it works and complete a few challenges to show their understanding. Success Criteria I can: – build a SODIS timer using the micro:bit – tinker with pre-written code to learn how it works – explain how to use a variable and conditional statement to track how long a water bottle has been in the sun – write my own conditional statement to indicate when the water is safe to drink – create two new variables to ensure the timer works well on cloudy and sunny days Resources Tutorial Final Code |
| Create | Students will work in small groups to design their own SODIS timer with the Climate Action Kit. Success Criteria I can build a SODIS timer with the Climate Action Kit that: – keeps track of how long water has been in the sun – clearly indicates when the water is safe to drink – works well on sunny and cloudy days and uses at least: – one light sensor Resources Blank Project |
*Irene Lee, Fred Martin, Jill Denner, Bob Coulter, Walter Allan, Jeri Erickson, Joyce Malyn-Smith, and Linda Werner. 2011. Computational thinking for youth in practice. Acm Inroads 2, 1 (2011), 32–37.
Use the following criteria to assess student learning. Students can:
Conversation
- Discuss why access to clean water is important
- Describe how people collect and clean water in countries with poor access and the important role women play in this process
- List the steps of the SODIS process and its pros and cons
- Identify the variable and conditional statement within the starter code and explain how they work together to track how long the water bottle has been in the sun (Use, Modify, Create)
Observations
- Make predictions about what certain segments of the code are responsible for and test those predictions (Use, Modify)
- Methodically test and debug their code to ensure it functions as intended (Modify, Create)
Products
- Add comments to the code to demonstrate their understanding of each block (Use, Modify, Create)
- Write a nested conditional to indicate when the water is safe to drink (Modify, Create)
- Design their own SODIS timer that satisfies provided criteria (Create)
- NGSS
- CSTA
- CCSS
- UN SDGs
Next Generation Science Standards
Grade 6-8
MS-ESS3-4 Construct an argument supported by evidence for how increases in human population and per-capita consumption of natural resources impact Earth’s systems.
MS-ETS1-1 Define criteria and constraints of a design problem with sufficient precision to ensure a successful solution, taking into account relevant scientific principles and potential impacts on people and the natural environment that may limit possible solutions.
MS-ETS1-4 Develop a model to generate data for iterative testing and modification of a proposed object, tool, or process such that an optimal design can be achieved.
Computer Science Teachers Association Standards
Grade 6-8
2-CS-02 Design projects that combine hardware and software components to collect and exchange data.
2-CS-03 Systematically identify and fix problems with computing devices and their components.
2-AP-11 Create clearly named variables that represent different data types and perform operations on their values.
2-AP-12 Design and iteratively develop programs that combine control structures, including nested loops and compound conditionals.
2-AP-13 Decompose problems and subproblems into parts to facilitate the design, implementation, and review of programs.
2-AP-19 Document programs in order to make them easier to follow, test, and debug.
Common Core State Standards for Mathematics
Grade 6-8
6.EE.A.2 Write, read, and evaluate expressions in which letters stand for numbers.
6.EE.B.5 Understand solving an equation or inequality as a process of answering a question: which values from a specified set, if any, make the equation or inequality true? Use substitution to determine whether a given number in a specified set makes an equation or inequality true.
6.EE.B.6 Use variables to represent numbers and write expressions when solving a real-world or mathematical problem; understand that a variable can represent an unknown number, or, depending on the purpose at hand, any number in a specified set.
6.EE.B.8 Write an inequality of the form x > c or x < c to represent a constraint or condition in a real-world or mathematical problem. Recognize that inequalities of the form x > c or x < c have infinitely many solutions; represent solutions of such inequalities on number line diagrams.
7.EE.B.4 Use variables to represent quantities in a real-world or mathematical problem, and construct simple equations and inequalities to solve problems by reasoning about the quantities.
United Nation’s Sustainable Development Goals
