In this activity, students construct a simple, effective moisture sensor that is then used to give warning of dry, damp or wet conditions1.
By the end of this activity, students should be able to:
- construct a simple moisture sensor
- conduct a series2 of experiments to investigate how various moisture sensors work.
Download the Word file (see below) for:
- introduction/background notes
- what you need and what to do
- student worksheets.
Related content
Read about the research in Satellite sensing – using remote sensing to make measurements ranging from storm damage to pasture growth. Sensing the Earth explores other techniques – like infrared3, radar4 and sonar5 – used to map and monitor the Earth’s structures, including New Zealand’s seismic activity.
Sensing robots tells the story of MARVIN – a Mobile Autonomous6 Vehicle for Indoor Navigation. Mechatronics explains the combination of electronics7, computer programming and mechanics8 that make robots like MARVIN function.
Activity ideas
Controlling resistance explores the concept of variable resistance9 by using a simple electrical circuit10.
You can also use micro:bit sensors to measure soil moisture.
- condition: An existing state or situation; a mode or state of being.
- series: An electrical circuit layout where components are connected one after the other so that the current passes in a single path through the components.
- infrared: Invisible electromagnetic radiation with a wavelength between approximately 0.75 micrometres and 1 millimetre. Infrared occurs between the red end of the visible light spectrum and microwaves. All things over a certain temperature (absolute zero) absorb and emit infrared radiation. Infrared radiation and observing technologies are used in many industries from medicine to finding people buried under rubble and by the military and others in night-vision goggles.
- radar: A method of detecting distant objects and determining their position, speed, or other characteristics by using very high frequency radio waves reflected from the objects’ surfaces.
- sonar: A method of detecting, locating, and determining the speed of objects through the use of reflected sound waves. A sound signal is produced, and the time it takes for the signal to reach an object and for its echo to return is used to calculate the object's distance.
- autonomous: A machine that is able to operate on its own with little or no human control. A lifeform that exists and functions as an independent organism.
- electronics: 1. The study of the behaviour and control of electrons. This field has expanded enormously with the discovery of semiconductors. 2. The generic term for hardware used to build electrical components.
- mechanics: A field of physics that studies the action of forces on objects made of matter.
- resistance: 1. The opposition to the flow of electric current through a circuit. 2. The ability to withstand harmful or unfavourable conditions, such as an infectious disease.
- electrical circuit: It is made up of a power source, other electrical components and an unbroken pathway along which an electric current exists or is able to pass.
