We started with the initial prompt: "Here is a battery, a lightbulb and some wires. Make it light up."
After the initial investigation we discussed the key elements that are needed to complete a circuit: a closed path, a voltage source (battery), a load (lightbulb).
Now students were asked to investigate more complex circuits with multiple bulbs and batteries.
In math class we were able to go a little more in depth into the relationship between the number of lightbulbs, batteries and the brightness of the light (the energy usage rate, which we came to learn in this case is directly related to the current). From some thought exercises, experimental observations (we also talked about independent and dependent variables) and a basic understanding of the mechanism of electrical current we we're able to derive an approximation of Ohm's Law for series circuits--basically doubling the voltage (number of batteries) makes the bulbs twice as bright and doubling the number of lightbulbs cuts the brightness in half.
This led us a little further into math as we talked about direct and indirect proportions; the green group even got a little into the characteristics graphs of direct (a line through the origin) and indirect proportions (a hyperbola with the axes as asymptotes).