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How Soap Pulls Germs Apart

8th grade nonfiction passage about why soap cleans hands: 262 words, six questions, an answer key and vocabulary.

8th grade nonfiction why soap cleans hands 262 words

How Soap Pulls Germs Apart

Water alone rinses away some dirt, but it does a poor job on greasy hands. Oil and water do not mix, so grease and the germs stuck in it cling to the skin while the water flows past. Soap solves the problem with a clever molecule that has two different ends.

One end of a soap molecule is attracted to water. The other end is drawn to oil and fat and avoids water. When you rub soap on wet hands, the oil-loving ends dig into grease and into the fatty outer layer that surrounds some germs, including certain viruses. The water-loving ends point outward toward the water. Under friction, soap molecules surround tiny bits of grease and pull them loose, forming little clusters called micelles. In some germs, soap can also pry apart the fatty coating, which breaks the germ open. Running water then carries the clusters down the drain.

This is why the way you wash matters. Rubbing creates friction that lifts dirt and loosens germs from the ridges of your skin. Health agencies suggest scrubbing for about twenty seconds, roughly the time it takes to sing a short song twice. Cover the backs of your hands, the spaces between your fingers, and the areas under your nails, since those spots are often missed. Dry your hands afterward, because damp skin spreads germs more easily.

Hand sanitizer with enough alcohol also works when soap is unavailable, but it does not remove visible dirt or grease as well. Plain soap and water, used patiently, remain the standard for clean hands.

Questions

  1. Why does water alone fail on greasy hands? in the text

  2. What are the two ends of a soap molecule like? in the text

  3. What are micelles? in the text

  4. About how long should a person scrub? in the text

  5. Why does rubbing your hands together help? think about it

  6. Why does sanitizer not fully replace soap and water? think about it

Words to know

molecule
a very tiny particle made of joined atoms
friction
the rubbing force between two things that touch
micelles
tiny balls of soap that trap bits of grease inside
viruses
extremely small germs that can make people sick
sanitizer
a liquid or gel used to kill germs on skin
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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 · 237 words · Flesch-Kincaid grade 3.2

Water can rinse off some dirt. But it does a poor job on greasy hands. Oil and water do not mix. So the grease, and the germs stuck in it, stay on your skin while the water runs by. Soap fixes this. A soap molecule has two different ends.

One end likes water. The other end likes oil and fat. It does not like water. When you rub soap on wet hands, the oil-loving ends dig into the grease. They also dig into the fatty layer around some germs, even some viruses. The water-loving ends point out toward the water. When you rub, soap molecules surround tiny bits of grease and pull them loose. They make little clusters called micelles. Soap can also break apart the fatty coat of some germs. Running water then rinses the clusters down the drain.

How you wash matters. Rubbing makes friction. Friction lifts dirt and loosens germs from your skin. Experts say to scrub for about twenty seconds. That is about as long as singing a short song two times. Wash the backs of your hands, between your fingers, and under your nails. People often miss those spots. Dry your hands after, because wet skin spreads germs more easily.

Hand sanitizer with enough alcohol also works when you have no soap. But it does not clean off dirt or grease as well. Soap and water are still the best.

▲ This passage · 262 words · Flesch-Kincaid grade 7

Water alone rinses away some dirt, but it does a poor job on greasy hands. Oil and water do not mix, so grease and the germs stuck in it cling to the skin while the water flows past. Soap solves the problem with a clever molecule that has two different ends.

One end of a soap molecule is attracted to water. The other end is drawn to oil and fat and avoids water. When you rub soap on wet hands, the oil-loving ends dig into grease and into the fatty outer layer that surrounds some germs, including certain viruses. The water-loving ends point outward toward the water. Under friction, soap molecules surround tiny bits of grease and pull them loose, forming little clusters called micelles. In some germs, soap can also pry apart the fatty coating, which breaks the germ open. Running water then carries the clusters down the drain.

This is why the way you wash matters. Rubbing creates friction that lifts dirt and loosens germs from the ridges of your skin. Health agencies suggest scrubbing for about twenty seconds, roughly the time it takes to sing a short song twice. Cover the backs of your hands, the spaces between your fingers, and the areas under your nails, since those spots are often missed. Dry your hands afterward, because damp skin spreads germs more easily.

Hand sanitizer with enough alcohol also works when soap is unavailable, but it does not remove visible dirt or grease as well. Plain soap and water, used patiently, remain the standard for clean hands.

■ Harder · 271 words · Flesch-Kincaid grade 9.4

Plain water can rinse away some dirt, but it performs poorly on greasy hands. Because oil and water refuse to mix, grease and the germs trapped within it cling to the skin while the water streams past. Soap overcomes this obstacle with an ingenious molecule that possesses two entirely different ends.

One end of a soap molecule is attracted to water, whereas the other end is drawn toward oil and fat and shuns water. When you rub soap onto wet hands, the oil-loving ends burrow into the grease and into the fatty outer layer that encloses some germs, including certain viruses, while the water-loving ends point outward toward the water. Under friction, soap molecules encircle tiny droplets of grease and pull them free, forming small clusters called micelles. In some germs, soap can also pry apart the fatty coating, which causes the germ to break open. Running water then sweeps the clusters down the drain.

For this reason, the way you wash matters considerably. Rubbing generates friction that lifts dirt and loosens germs from the ridges of your skin. Health agencies advise scrubbing for roughly twenty seconds, about the time it takes to sing a short song twice. Be sure to cover the backs of your hands, the spaces between your fingers, and the areas beneath your nails, since these spots are frequently overlooked. Dry your hands afterward, because damp skin transfers germs more readily.

Hand sanitizer containing enough alcohol also works when soap is unavailable, although it does not remove visible dirt or grease as effectively. Plain soap and water, used patiently, remain the standard for clean hands.

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 molecule, friction, micelles, viruses and sanitizer 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 3 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 5 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 "How Soap Pulls Germs Apart"?

It was written for 8th grade. It has 262 words and works out to a Flesch-Kincaid grade level of about 7.0. 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. 4 ask for something the text says directly and 2 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 3 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.

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