Luminaria

Make your own luminaria!

Understanding basic circuits comes from experience, and many children haven’t had that experience. But once your students have mastered the basics of lighting a light bulb with a battery, there are limitless possibilities to the kinds of investigations they can engage in. This activity expands your students’ investigations by focusing on new ways of wiring and introducing a holiday tradition from the Southwest U.S.

Preparation

Test the batteries and bulbs before this activity to make sure that they are all working. You can do this by lighting each bulb up with a battery that you know works, and then testing a working bulb with each of the other batteries.

If you have not done so yet, try the Lighting a Light Bulb activity. It serves as a good foundation for this activity.

Resources

Figure 1

Figure 2

Figure 3

Suggested Materials

D or C-cell batteries (2 per team)
Stripped individual light bulbs (4 per team)
Stripped wire pieces, 6 inches long (2 pieces per team)
Masking tape or electrician’s tape
Small paper lunch bags (white or brown) (1 per team)

Opening Discussion

Ask your students to think about what they learned in the Lighting a Light Bulb activity. Did anyone discover how to light up 2 bulbs at a time with 1 battery? How about 3 bulbs? If anyone lit multiple bulbs with 1 battery, ask them if the bulbs were brighter, less bright or the same as 1 bulb and 1 battery. Is there a way to light up 2, 3 or 4 bulbs with 1 battery and have them be as bright as 1 bulb?

The Challenge

Can you light 3 bulbs at the same time with just on battery?

Doing the Activity

Have your students work in teams of 2 for this activity.
Distribute 1 battery, 3 bulbs and 2 pieces of wire to each team and give them their challenge.

Let’s Talk About It

After 10–15 minutes, when some teams have lit their bulbs, bring your students together to talk about what they’ve done. It is possible that no children will have achieved the goal, but bring them together anyway. Have each team share what they’ve tried. What has worked and what hasn’t? If any teams have discovered a new way of wiring 3 bulbs so that they light up, have them share their discovery with the rest of the group. If another team has a different way (working or not) that they are willing to share, have them share and compare it with the first team. What is different about the way each team has wired their bulbs? (for a description of the different ways of wiring the bulbs, see Suggestions in the “Make it Better” section).

Build On What They Talked About

Give teams another battery, and have them return to the challenge to try to light their 3 bulbs together so that they are as bright as possible. Can they use both batteries at the same time to light their bulbs?

Take a break again after 5-10 minutes and have students share what they’ve tried. How can they use both batteries at the same time to light the bulbs? Are the bulbs the same brightness, brighter or dimmer with 2 batteries than with 1? Have them return to the challenge until all teams have lit their bulbs.

Once each team has lit 3 bulbs with 2 batteries, hand out a paper bag to each team, have them tape the batteries so that they stay together, and tape their wired bulbs to the batteries so that the lights remain on. Students should then open up the paper bag, place it on the table or desk in front of them so the bag stands up, and put the lit bulbs and their batteries in the bottom of the bag. When everyone has their bulbs in place, turn off the lights—the bags will be glowing beautifully! Have your students arrange the bags on the ground any way they’d like. Suggest that they might make a path with the lit bags lining either side of this path, and have them walk through it.

Ask your students if any of them have seen luminaria before. In parts of the U.S., many people make bags like these using candles instead of batteries and bulbs, with sand in the bottom to keep the candles in place. They call these bags “luminaria”, and they line walkways, driveways and streets with lots of them at night on Christmas Eve, New Year’s Eve and for other special occasions like Las Posadas. What are some special occasions that your students could use luminaria for?

Suggestions

This activity focuses on 2 different ways of lighting multiple light bulbs. When presented with this challenge, most children will first try to light their bulbs by stringing them together in a line, like this (See Figure 1).

This is known as wiring in “series”. This method looks like the string of holiday lights, and will work if you have enough power. But the more lights that you add to the string, the dimmer the lights will get. This is because the same amount of power is running through the string of lights, but as you add more lights, more power is needed to light them. By the time you have 3 lights in a row, they need much more power than one bulb, so they will either be very dim, or will not light at all. Here is a second way of twisting the bulbs together (Figure 2).

These bulbs are not in a line. A wire from each bulb is twisted together with the others. The second wire from each of the bulbs are all twisted together. This leaves 2 connections, each made up of 3 wires twisted together. This is known as wiring in parallel. When these two 3-wire connections are touched to the 2 ends of a battery, all 3 bulbs will light up just as bright as when 1 bulb is lit up with the battery. This is because each bulb creates its own path, drawing energy from the battery. You’re not getting something for nothing here though—this method will drain power from the battery more quickly than wiring in series. When your students are ready to use 2 batteries, they will discover that the batteries need to be touching end-to-end, facing in the same direction, like this (Figure 3).

By touching the wires to the 2 ends of this setup, they will be able to light their bulbs more brightly than with a single battery. Do not show children these methods—let them discover them themselves. If the class is struggling, find ways to ask questions that will lead them to discovering these methods themselves.