A planet is not a bucket you fill with heat. It sits at the balance point where the energy it radiates away exactly matches the sunlight it absorbs. This bench runs that balance as one equation: C·dT/dt = ASR − OLR.
ASR, the absorbed sunlight, depends only on how bright the Sun is and how much the surface reflects (its albedo) — a flat bar that does not care about temperature. OLR, the outgoing infrared, climbs steeply with temperature (Stefan–Boltzmann's σT⁴) and is throttled by the greenhouse factor f. Turn a knob and OLR chases ASR until the two bars level off at a new equilibrium.
The blanket is logarithmic: f rises a fixed step for every doubling of CO2, so 1×→2× and 2×→4× add roughly the same bounded slug of warming — never a runaway. Bare rock sits near −18 °C; today's blanket lifts it to about +15 °C, the greenhouse warming falling straight out of the physics with no fudge factor.
This is a deliberately simple zero-dimensional model: one global temperature, no ice–albedo feedback, no clouds, no tipping points. It shows why the mechanism is settled and how doubling is bounded — the harder question of exactly how much (climate sensitivity, feedbacks) is a story for later classes.
Something in the simulation stopped unexpectedly — the lesson continues without it. You can move on; nothing you did was wrong.