The breadboard is where things all come together. A breadboard allows you to quickly connect components without having to use actual solder. This makes prootyping, and learning, very fast.
The key to understand is how the connections run underneath. Each row runs for just the 5 or 6 pins on that column. On the sides are power rails that often run the entire length of the breadboard. This isn’t always true and I’ll add photos below to help understand while it doesn’t always work like that.
Any wire or component plugged into Row 1 a through e is connected to any other wire or component plugged into that group of holes. Note that f through j on the other side is not connected to a through e unless you run a jumper wire or component between them.
Note that there is very little consistency in how breadboards are labeled. Some have the numbers the same top to bottom, others hare top to bottom on one side and bottom to top on the other. Quality also varies from manufacturer to manufacturer. If you are teaching a class I suggest sourcing identical boards for your students. Especially if you are teaching a virtual class.
If you need more details – the best guide I’ve found on how to use a breadboard is at sciencebuddies.org.
You’ll use jumper wires to create connections between components and your Microcontroller. I suggest using pre-made jumper wires. Note that it is also helpful to have a blend of Male to Male, Male to Female and Female to Female wires.
It is common to use red wires for positive voltage and black wires for negative voltage. I’ve seen that some people use Red for +5V and Orange for +3.3V. When it comes to I2C, Adafruit uses White for SDA and Green for SCL. There is a page that lists some colors for other vendors, and they aren’t consistent. As long as the wire is connected correctly it doesn’t matter the color on the wire.
When you follow the diagrams in these guides it might be easier to use the same colors to help keep track, but it isn’t required. With larger projects it is easier though. And if you are teaching a large group I suggest making sure each student has a good supply of wires and that you try to get the class all using the same colors for each step.
You can purchase the ELEGOO 120pc wires on Amazon, but am mixed on the quality at this time. I recently purchased the ones from Chanzon on Amazon and will post how they compare soon.