ThingSpeak has APIs for collecting data produced by sensors and APIs for reading that data from applications. Think of an IoT project as two parts. One part of the project is where you need to program a thing to send data. And, the second part is where you want to see that data. ThingSpeak sits in the middle and makes it handy to do both, as Marcelo Rovai points out. Once you have a system like Marcelo’s set up, you can take advantage of integrated online MATLAB Analytics.
Marcelo has put together a great tutorial that uses ThingSpeak in the middle to collect data from sensors and then display the sensor readings on a custom Android app running on a mobile phone. He uses the MIT App Inventor to create a custom Android app to see the sensor data and status of the system. This project uses easily accessible hardware to build a proof-of-concept IoT system to monitor air temperature, humidity, soil temperature, soil humidity, and luminosity. Other people could modify this project with different sensors or actuators and build something for their own purposes or build a prototype for your next meeting at work.
Check out the full project tutorial on Arduino Project Hub and Instructables. Marcelo provides all of the parts, code, and instructions to make your own prototype IoT system monitored and controlled by a mobile app.