Breadboard + Multimeter
CSA-101 §11.1 + §11.2. Build the Lab 1.1 flashlight circuit on a 5-slot virtual breadboard. Probe with the virtual multimeter to measure voltage drop. No-kit fallback for the Week 1 lab. CSA-101 catalog.
What you are doing
Lab 1.1 asks you to build a flashlight: a 9V battery, a switch, a current-limiting resistor, and an LED, wired in series so the LED lights up when the switch is closed. This tool gives you a 5-slot breadboard to drop the components into and a multimeter to probe between them. Pick a component from the palette, click an empty slot, watch the slot turn green if it matches the canonical Lab 1.1 placement or red if not. When all 5 slots are correct, click Energize and the LED lights up.
Switch the multimeter into voltage mode and click two probe points; the live readout shows the voltage drop between them. Probe across the battery and you read about 9 V; probe across the resistor and you read the drop the resistor causes; probe across the LED and you read the LED's forward voltage. Same readings the $15 physical multimeter shows.