Skip to the content
Peabody TeachFor teachers and grown-ups

Why One Bad Bulb Darkens a String of Lights

6th grade nonfiction passage about series circuits: 224 words, six questions, an answer key and vocabulary.

6th grade nonfiction series circuits 224 words

Why One Bad Bulb Darkens a String of Lights

Many families have unpacked a string of holiday lights, plugged it in, and found the whole string dark. Somewhere along the wire, one small bulb has failed. Yet the other bulbs seem fine. Why should one bad bulb put out the rest?

The answer is in the way the bulbs are connected. Electricity flows only along a closed path, called a circuit. Think of it as a loop that carries electric current from the power source, through each part, and back again. If the loop is broken anywhere, the current stops everywhere.

On some older strings, the bulbs are wired in series. That means they sit one after another on a single path, like beads on a necklace. The current has no other way to go. When the thin wire inside one bulb, called the filament, breaks, the path is cut, and every bulb goes dark.

Compare that with the lamps in a house. They are wired in parallel, so each lamp has its own branch off the main wires. If one lamp burns out, the electricity keeps flowing to the others. That is why the rest of the room stays lit.

Many newer strings include a tiny part in each bulb that keeps the path complete if the filament fails, so the others stay lit. Always unplug a string before touching its bulbs.

Questions

  1. What is a circuit? in the text

  2. What happens to the current if the loop is broken anywhere? in the text

  3. What does it mean for bulbs to be wired in series? in the text

  4. How are the lamps in a house wired, and why does that help? in the text

  5. What should you do before touching the bulbs of a light string? in the text

  6. Why is a necklace of beads a good picture of a series circuit? think about it

Words to know

circuit
a closed path that electricity flows around
current
the flow of electricity through a wire
series
one after another along a single path
parallel
side by side, each on its own separate path
filament
the thin wire inside a bulb that glows
Share

One passage, three levels

The same topic and facts written three ways, so a mixed class can read and talk about one text. Each group’s sheet shows only a shape; the key says which is which.

● Easier · 218 words · Flesch-Kincaid grade 2.9

Many families unpack a string of holiday lights. They plug it in. The whole string is dark. Somewhere, one small bulb has failed. Yet the other bulbs look fine. Why does one bad bulb put out the rest?

The answer is in how the bulbs are connected. Electricity flows only along a closed path. This path is called a circuit. Think of a loop. Electric current goes from the power source, through each part, and back again. If the loop is broken anywhere, the current stops everywhere.

On some older strings, the bulbs are wired in series. They sit one after another on a single path, like beads on a necklace. The current has no other way to go. Inside each bulb is a thin wire called the filament. When it breaks in one bulb, the path is cut. Every bulb goes dark.

The lamps in a house are different. They are wired in parallel. Each lamp has its own branch off the main wires. If one lamp burns out, the electricity still flows to the others. So the rest of the room stays lit.

Many newer strings have a tiny part in each bulb. It keeps the path whole if the filament fails. So the others stay lit. Always unplug a string before you touch its bulbs.

▲ This passage · 224 words · Flesch-Kincaid grade 4.7

Many families have unpacked a string of holiday lights, plugged it in, and found the whole string dark. Somewhere along the wire, one small bulb has failed. Yet the other bulbs seem fine. Why should one bad bulb put out the rest?

The answer is in the way the bulbs are connected. Electricity flows only along a closed path, called a circuit. Think of it as a loop that carries electric current from the power source, through each part, and back again. If the loop is broken anywhere, the current stops everywhere.

On some older strings, the bulbs are wired in series. That means they sit one after another on a single path, like beads on a necklace. The current has no other way to go. When the thin wire inside one bulb, called the filament, breaks, the path is cut, and every bulb goes dark.

Compare that with the lamps in a house. They are wired in parallel, so each lamp has its own branch off the main wires. If one lamp burns out, the electricity keeps flowing to the others. That is why the rest of the room stays lit.

Many newer strings include a tiny part in each bulb that keeps the path complete if the filament fails, so the others stay lit. Always unplug a string before touching its bulbs.

■ Harder · 257 words · Flesch-Kincaid grade 6.9

Many families have unpacked a string of holiday lights, plugged it in, and discovered that the entire string remains dark. Somewhere along the wire, a single small bulb has failed, yet all of the other bulbs appear to be in perfect condition. Why should one bad bulb be able to put out the rest?

The answer lies in the way the bulbs are connected. Electricity flows only along a closed path, which is called a circuit. You can think of a circuit as a loop that carries electric current from the power source, through each part, and back to the source again. If the loop is broken anywhere along its length, the current stops everywhere.

On some older strings, the bulbs are wired in series. That means they sit one after another on a single path, like beads on a necklace, and the current has no alternative route. When the thin wire inside one bulb, called the filament, breaks, the path is cut, and every bulb goes dark.

Compare that arrangement with the lamps in a house. Those lamps are wired in parallel, so each lamp has its own branch off the main wires. If one lamp burns out, the electricity continues to flow to all of the others, which is why the rest of the room stays lit.

Many newer strings include a tiny part in each bulb that keeps the path complete if the filament fails, so that the other bulbs remain lit. It is always wise to unplug a string before touching its bulbs.

Download as one PDF

How to use it

  1. Press Read it big (or B) to put the text on the projector, or Full screen (F) to fill the whole screen.
  2. Ask the questions one at a time and use Show answer when the class has decided. A shows or hides every answer.
  3. Print student copy for the class, or Print with answers for yourself.

Ideas for class

  • Before reading, put circuit, current, series, parallel and filament on the board with their meanings from the Words to know section and have students predict what the text will be about.
  • Read it aloud once while students follow along, then have them reread it alone or with a partner. At a calm 100 words a minute it takes about 2 minutes to read aloud.
  • Use the Read it big button (or B) to put the text on the projector, and Show answer on one question at a time so the class commits to an answer first.
  • Question 6 asks the reader to infer. Ask students to point to the words in the passage that led them to their answer.
  • Ask students to write one question the passage did not answer, then look for the answer in a book or on a classroom screen.
  • Print the student copy for independent work and keep the answer-key copy for yourself.

Related

Questions

What reading level is "Why One Bad Bulb Darkens a String of Lights"?

It was written for 6th grade. It has 224 words and works out to a Flesch-Kincaid grade level of about 4.7. That is a formula's estimate from sentence length and syllables, and it is not a Lexile or a guided reading level, so check it against your students.

What do the questions ask?

There are six. 5 ask for something the text says directly and 1 ask the reader to work something out from clues. Each has an answer in the key, and the answers are written as a teacher would accept them, not as the only possible wording.

How long does it take to read?

About 2 minutes read aloud at 100 words a minute. For a one-minute fluency check, paste it into the fluency timer and use the word count.

Can I print it?

Yes. Print student copy gives the passage, the questions with lines to write on, and the word meanings. Print with answers gives the same page with the answers filled in. Both are made in your browser.

Is this passage from a published book?

No. It was written for Peabody Teach, so there is no book to buy and no login to read it.

Nothing you do here is sent to us. No sign-in, no ads.