Bringing maker education and computational thinking to the classroom.
Monitor My Plant
7 (Could work for grades 5 - 8)
120 minutes (approximately 2 class periods)
Students learn about the gator:soil sensor and how they can use it to monitor when a plant needs to be watered. Students calibrate the gator:soil for the value of dry soil and wet soil. Then they program the micro:bit to monitor the soil moisture using the gator:soil and the 5 LEDs and speaker on the gator:bit to indicate moisture levels and when the plant needs to be watered. This could work in a science class that is growing plants for another experiment or in any classroom that has plants. Students don’t have to each have their own plant, they could monitor any plants in the classroom. Multiple students can monitor one plant.
micro:bit, soil moisture, watering plants, sensors, middle school, coding
Students should have some experience programming the micro:bit. Provided they have worked through some of the tutorials on the MakeCode website they should be able to complete the activity.
Introduction / Motivation:
(Bring out a plant that hasn’t been water in a while, make sure that the leaves a drooping, the soil is dry, and overall doesn’t look healthy). How does this plant look to you? (Write list on the board of students observations, hopefully at least one of them will bring up that it looks like the plant needs water). How do you know when you need to water a plant? (Make list on the board) Do you think you can ever water a plant too much? (If students think this answer is no, show them these pictures).
How can we make sure to always water a plant exactly when you need to? (If your students are familiar with the sensors and the micro:bit, hopefully some of them will bring up how they could use them. If students aren’t familiar with the sensors, ask them about things they know to alert them that something needs to happen like a timer on the microwave or alarm clock. For example you could say… Just like your alarm clock wakes you up in the morning, you can make an alarm to let you know when you need to water your plant.)
Each of you is going to create a system to monitor the soil moisture level of a plant. As a class we are going to come up with a set of criteria for what it must include.
Clearly explain the step-by-step procedure to follow to conduct the hands-on activity. Make sure to include connections to engineering and address activity objectives. To clarify the activity setup and procedure, place images, photographs and diagrams throughout this section and the activity write-up. Use figure numbers if the image is referenced in the text. Include metric units.
Make sure you are familiar with the different capabilities of the gator:bit and micro:bit. The main ones to focus on here are the different ways to represent information using the 5 LEDS on the gator:bit controlled by pin P12, the speaker controlled by pin P0, and the 25 LEDs on the micro:bit itself (see Figure 1). In addition, make sure you are familiar with the gator:soil sensor and how to wire it, the two main things to remember are:
For more information about the gator:soil sensor see the hookup guide. The gator:soil returns values between 0 and 1. These decimals can be hard for students to understand and interpret. I recommend having students multiply the result by 100 to make the results easier to understand. I support this in the tutorial and there is a MakeCode block math that will do this for the students. I don’t think a long explanation is necessary here simply saying something like converting a decimal number to a percent should suffice.
Figure 1: Ways to use the gator:bit/micro:bit to represent information.
Before the Activity
With the Students
Figure 2: Suggested wiring diagram for the gator:soil and an actual picture of wiring up the sensor.
Figure 3: Sequence of moves in MakeCode to add the gator:soil sensor.
Figure 4: Sequence of moves in MakeCode to add the neopixel library