Following-on from the comment by Mike Bell @drmibell , I tutor an after-school IoT Club for 11-15 year olds here in the UK.
I've given the age range of the students as different countries call this group by different titles.
I've been doing this for over 3-years (since I retired) and have tried different pieces of hardware (e.g. Raspberry Pi(es) of various vintages) before building the WiFi-Server towers (using RPi-Z-W) as shown below.
The towers connect to a WiFi router which in turn connects to the Internet via the school's network.
I recently bought a couple of RPi-4B's (for my personal use at home) and reckon if I had to start again I might well consider basing the IoT Club's network on those latest devices.
i.e. run multiple copies of Node-RED in each RPi-4B.
I've made-up 20 or more breadboards populated with Wemos D1 Minis. All this kit is kept in a locked cupboard in the IT classroom and brought out each time I tutor the Club. I bring in to school a couple of storage boxes containing mains extension leads, box of LEDs, resistors and connecting wires for the breadboards.
The students have access to 36 PCs arranged in clusters of six in the IT classroom and I usually have no more than ten students on each session. Purely because of the task of getting around to each student and practicalities of hardware limitations.
Each student plugs a WiFi dongle into their chosen PC to make it WiFi-enabled. Each student is allocated a dedicated RPi-Z-W (that is running Node-RED and Mosquitto) for the duration of the term.
I normally handle a new group of students every term, but some students have got so addicted to the IoT Club and have been with me for the whole of the 3-years. These particular students help some of the new students in between tackling some dedicated-personal projects I've set them.
Each term I normally start off with an overview of IoT and then go on to explain about breadboards. I then get them to wire up a single LED which is driven by the Wemos D1 Mini. This is extended to handle three LEDs and thus make a traffic light. Triggers and delays are introduced to make the LEDs flash.
Note: The reason for using Wemos devices is they are inexpensive, so if a student should destroy one - no one will get upset. Much safer than plugging things into a Raspberry Pi. They are flashed with 'ESP-Easy' and given a fixed IP. This makes controlling things very easy as drivers for a number of popular 'items' are included. For example, driving LEDs, relays, PWM, LCD panels, temperature, humidity, pressure sensors, strain gauges, I2C, NeoPixels, etc.
Next step is using something like 'OpenWeather' to collect weather reports from around the world. This information is initially shown using a set of 'debug' nodes, and then in later sessions the students use small LCD panels (on the Wemos) to show the information.
The school uses Google-Classroom to deliver its main-stream teaching material and have given me an account so I can create and deploy tutorials to the students that attend the IoT Club.
Hope this helps - if you are interested in more information please don't hesitate to contact me.
Here's a link to the Solar-Powered Weather Station that one of my students tackled last year.
Regards, David.
