• Demonstration: Set up a similar situation to that in the problem, with three dissimilar lightbulbs connected in series. Page 616 in Serway and   Faughn's College Physics¹ shows a picture of such a demonstration.
• You could also work the demonstration sort of backward. Instead of using bulbs with different power ratings, use four bulbs with the same power rating but different brightness. Then ask the students to figure out how the bulbs are connected in the circuit.
• One elegant way to set up this demonstration is to use a four-bulb "bath bar," a strip of lights at the top of a bathroom mirror. Such bars are readily available at home-supply stores. It's not a horribly difficult project to change the wiring of the bar so that some of the bulbs are in series with one another.²
• Laboratory exercise: It is worth spending a full lab period playing with lightbulbs in some manner. One possibility is to obtain plenty of bulbs of two different power ratings.³ A standard laboratory power supply set at about 5 volts, or just four C cells in a holder, will provide an appropriate voltage source. What could the assignment be?
  • Draw a few circuits -- say, one with three bulbs in series, one with three bulbs in parallel, one with a combination of series and parallel bulbs. Indicate the rating of each bulb. Ask students to predict which bulb should be brightest in each case. Then have them connect the bulbs to test their predictions.
  • Have students measure the current through and voltage across each bulb with a multimeter.⁴ Then have them use the bulb ratings and a chart (as in the homework problem) to calculate the current through and voltage across each bulb. Be sure they connect the meter in series to measure current and in parallel to measure voltage -- it's easy to blow out the fuses in the meters if they connect ammeter leads in parallel with a resistor!

Notes
1. Raymond Serway and Jerry Faughn, College Physics, 7th ed. (Belmont, CA: Brooks/Cole, 2006).
2. Development Committee member Martha Lietz of Niles West High School presented such a demonstration the AP Physics Exam Reading in 1995.
3. RadioShack® offers its own miniature bulbs (for example, part number 272-1130, a 6.3 V, 250 mA with a screw base). What do you screw the bulbs into? Try RadioShack® part number 272-357. You can use these with either alligator clips or stripped wires.
4. A good, cheap multimeter is RadioShack®'s analog number 22-218. Pedagogically, I strongly prefer an analog meter; students actually have to read the meter and see the needle move, rather than just copy some numbers off a digital meter's screen.