CCRA.W.2: Writing Informative and Explanatory Texts

Overview

Lesson Procedure

60-60 minutes of class time across 5 phases.

1. Warm-Up5 minutes
2. Direct Instruction20 minutes
3. Guided Practice15 minutes
4. Independent Practice15 minutes
5. Closure5 minutes

1. Warm-Up5 minutes

   Warm-Up Prompt

   "A front-door key is a strip of metal with a jagged edge. In two sentences, explain how you think the lock can tell the right key from a wrong one. You may guess; we will check your ideas today."

   Take four answers and write them on the board without judging them. Most guesses are partly right (the shape of the edge matters) and vague about how. Tell students that turning a vague idea into a clear, accurate explanation is the job of CCRA.W.2, and that they will return to their guesses at the end of class.

2. Direct Instruction20 minutes

   Explain the difference between the two purposes in the standard. To examine is to work out how an idea fits together; to convey is to make it clear to a reader who was not there. Then name the three choices a writer makes:

   • Selection: keep the facts that explain the process; cut true but unhelpful details.
   • Organization: choose a structure that fits the idea (definition, classification, comparison, cause and effect, process), and use headings and transitions so the reader can follow it.
   • Analysis: explain how the parts work together and why, instead of listing facts side by side.

   "Clearly and accurately" are both required: a clear explanation of a wrong idea fails the standard. Show the progression table so students see how the demands rise from grade 6 to grades 11-12.

   Progression of CCRA.W.2 in grades 6-12 (short paraphrases of the grade-level standards)

   Grade-level standard	Band	What this band adds
   W.6.2	Grade 6	Introduce a topic and organize it with strategies such as definition, classification, comparison and cause and effect; develop it with facts, definitions and details; transitions, precise vocabulary, a formal style and a conclusion
   W.7.2	Grade 7	Preview what is to follow; transitions that create cohesion; a conclusion that supports the explanation
   W.8.2	Grade 8	Organize ideas into broader categories; well-chosen details; varied transitions
   W.9-10.2	Grades 9-10	Complex ideas conveyed clearly and accurately, with important connections and distinctions; sufficient facts and extended definitions; precise language to manage complexity; objective tone; a conclusion that can state implications or significance
   W.11-12.2	Grades 11-12	Each new element builds on the one before to form a unified whole; the most significant facts, developed thoroughly; metaphor, simile and analogy used to manage complexity
   WHST.6-8.2	Grades 6-8, history, science and technical subjects	Informative texts in the disciplines, including historical events, scientific procedures and technical processes; formal style and objective tone
   WHST.9-10.2	Grades 9-10, history, science and technical subjects	Connections and distinctions in discipline content; varied transitions and sentence structures; a style suited to the discipline
   WHST.11-12.2	Grades 11-12, history, science and technical subjects	A unified whole built from the most significant facts; techniques such as analogy to manage complex technical ideas

   Work through the five examples. They use a separate small topic, how a photoelectric smoke alarm detects smoke, so that the lock texts stay fresh for practice. In this kind of alarm, a small light shines across a dark chamber, and a light sensor sits off to one side, out of the beam.

   • Selecting content

     Four notes: (a) a small light shines across a dark chamber; (b) smoke particles scatter some of that light onto a sensor; (c) the plastic case comes in white or almond; (d) alarms should be tested once a month.

     Result: Keep (a) and (b): they explain how detection works. Cut (c), which is true but explains nothing. Note (d) is useful safety advice, but it belongs in a different text, one about using alarms.

   • Organizing a cause-and-effect chain

     Scrambled steps: the alarm sounds; smoke enters the chamber; scattered light reaches the sensor; the particles scatter the light.

     Result: Order: smoke enters the chamber, so the particles scatter the light; some scattered light reaches the sensor, and as a result the circuit sounds the alarm. The transitions (so, as a result) show cause and effect, not only sequence.

   • Precise, domain-specific language

     Vague draft: The light thing sees the smoke and then it goes off.

     Result: Revision: When smoke particles scatter the beam, some light reaches the light sensor, and the sensor's signal triggers the alarm. Each vague word ("thing," "sees," "it") becomes a named part or action.

   • Analysis, not only listing

     Listing: There is a light. There is a sensor. The sensor is at an angle.

     Result: Analysis: The sensor is placed out of the beam's path on purpose, so it receives light only when something in the chamber scatters it. The design turns the presence of smoke into the presence of light.

   • An analogy and its limit (grades 9-12)

     Goal: help a reader picture why smoke makes light reach the sensor.

     Result: Analogy: like dust that becomes visible in a sunbeam crossing a dark room, smoke shows up only when it scatters light. Limit: the alarm does not see smoke the way a person does; it measures how much light reaches the sensor.

   Hand out the research notes on the pin tumbler lock and read them together. Use Diagram 1 to point to each part as it is named. Tell students that the notes are complete but not selected or organized: some notes are not needed to explain how the lock works.

   1Where it is used. The pin tumbler lock is the kind of lock found in many front doors and padlocks that open with a flat key with a jagged edge. Linus Yale Jr. improved and patented versions of it in the 1860s.

   2Parts. An outer housing (also called the shell) and, inside it, a cylinder called the plug, which turns when the right key is in it. The keyway is the slot in the plug where the key goes.

   3Pin stacks. Holes are drilled through the housing and into the plug, often five or six in a row. Each hole holds a spring at the top, then a driver pin, then a key pin at the bottom that touches the key. Key pins come in different lengths; driver pins are often all the same length.

   4Shear line. The thin gap where the outside of the plug meets the inside of the housing. The plug can turn only if nothing crosses this gap.

   5Without a key. The springs push the pins down, so each driver pin sits partly in the plug and partly in the housing, blocking the shear line.

   6With the right key. Each cut on the key (the pattern of cuts is called the bitting) lifts its key pin to the right height, so the top of every key pin lines up with the shear line. The driver pins rest entirely in the housing, and the plug turns. A cam on the back of the plug pulls the bolt.

   7Wrong key. If even one cut is too high or too low, that pin stack crosses the shear line and the plug will not turn.

   8Example lock (numbers invented for this lesson). 5 pin stacks; each key pin can be one of 6 lengths.

   9Master keys. In some buildings, a small extra pin, called a master pin, sits between the key pin and the driver pin. It creates a second gap in the stack, so two different keys, such as a tenant's key and the building manager's master key, can each line up a gap with the shear line.

   10Side notes. Brass is a common material for pins because it resists rust. Keys are often cut on a machine that traces an original key.

3. Guided Practice15 minutes

   Read the model explanation aloud. Students highlight every term the writer defines in one color and every transition or heading in another. Then walk through the steps.

   1A front-door lock makes a decision every time someone pushes a key into it: turn, or stay still. The pin tumbler lock, the type found on many front doors and padlocks, makes that decision with a row of small spring-loaded pins. This explanation describes the parts of the lock, how the pins block it, and how the right key, and only the right key, sets them free.

   2The parts. The lock has two main pieces. The outer housing stays fixed in the door, and inside it sits the plug, a cylinder with a slot for the key called the keyway. A row of holes, usually five or six, runs through the housing and down into the plug. Each hole holds a pin stack: a spring at the top, a driver pin below it and a key pin at the bottom, resting in the keyway. The key pins are made in different lengths.

   3How the pins block the plug. The plug can turn only at the shear line, the thin gap where the plug meets the housing. With no key in the lock, the springs press every stack down. Each driver pin then sits partly in the housing and partly in the plug, like a bolt slid across the gap, so the plug cannot rotate.

   4How the right key opens it. The edge of a key is cut into a pattern of peaks and valleys called the bitting. As the key slides in, it pushes the key pins up. When the key is all the way in, each cut holds its key pin at just the right height: the top of every key pin meets the shear line, and every driver pin sits entirely in the housing. Nothing crosses the gap now, so the plug turns, and a cam on its back pulls the bolt out of the door frame.

   5Why a wrong key fails. A different key has at least one cut at a different depth. If a cut is too shallow, it lifts its key pin too far, and the key pin itself crosses the shear line. If a cut is too deep, the key pin sits too low, and its driver pin reaches down across the line. Either way, one pin is enough to block the plug, so every cut on the key matters.

   6Why the design works. Because every stack must be right at the same moment, the number of possible keys multiplies with each stack that is added. A lock with more stacks, or more possible pin lengths, has far more possible keys, so a stranger's key is less likely to fit by chance. The design also depends on precision: a key pin made slightly too long can stop even the right key from working.

   7In short, a pin tumbler lock turns the jagged edge of a key into a set of heights, and it opens only when every height is right. When a key sticks, one possible cause is a key worn down so that one pin no longer stops exactly at the shear line.

   1. The introduction previews. Ask: "Which sentence in paragraph 1 tells the reader what is coming?" Teacher note: the last sentence lists the parts of the explanation in the order the headings follow.
   2. Terms are defined where they first appear. Ask students to find two terms that are defined in the same sentence that introduces them. Teacher note: "keyway" (paragraph 2) and "bitting" (paragraph 4) are both defined at first use.
   3. A comparison helps a reader picture the idea. Ask: "In paragraph 3, what does the comparison to a bolt slid across a gap help a reader see?" Teacher note: it shows why a pin crossing the gap stops the plug, the way a door bolt holds a door.
   4. Analysis goes beyond the steps. Ask: "Paragraph 6 adds no new step. What does it add?" Teacher note: it explains why the design works and what it depends on, which is analysis.
   5. The conclusion states an implication. Ask: "Does paragraph 7 only repeat the explanation?" Teacher note: its second sentence applies the idea to a sticking key, an implication a reader can use.

   Grades 6-8 focus: the introduction, defined terms, headings and transitions. Grades 9-12 focus: how each section builds on the one before, and where the explanation moves from description to analysis.

4. Independent Practice15 minutes

   The weak draft below was written for this page with errors on purpose: it is vague, out of order and in places inaccurate. It is not a model. Students rewrite it using the research notes. Grades 6-8 write one accurate, organized paragraph of 100-150 words that defines at least two terms. Grades 9-12 write two or three paragraphs with headings, including one sentence of analysis that explains why the design works.

   1Locks are really cool and everyone uses them. A lock has a big pin inside it that holds it shut. When you put your key in, the pins fall down into the grooves on the key and then the lock opens. The key has to be the right one or it won't work. Also there are springs. The springs make it work better. Some locks have master keys. Locks are made out of metal. That is how a lock works, and it is very interesting.

   Look for: accurate movement of every part, named parts in place of vague words, a clear order from parts to function, and no filler such as "really cool." The quiz questions on this draft serve as the key; do not hand it out before students write.

5. Closure5 minutes

   Exit ticket: Return to the warm-up guesses on the board. Each student picks one guess and writes one sentence that corrects or sharpens it, using at least one term from today. Look for accurate use of "shear line" and of at least one other term from the notes.

   Teacher note: the lock texts explain how a lock works so students can practice explanatory writing. They do not teach how to open a lock without its key; keep discussion on the mechanism and on the writing.

   For homework: students use the fact sheet below. Its facts were written for this page, and its test data are invented. Its paragraphs are numbered 1-7.

   1What it is. A vacuum flask, often called a thermos, is a bottle with two walls, one inside the other. Almost all of the air has been pumped out of the space between the walls, leaving a near vacuum. The Scottish scientist James Dewar designed a vacuum flask in 1892 to keep liquefied gases cold in his laboratory.

   2Three ways heat moves. Conduction passes heat through matter by contact, as when a metal spoon warms up in hot soup. Convection carries heat by the movement of a liquid or a gas, as when warm air rises from a heater. Radiation carries heat as infrared light, which can travel through empty space.

   3Blocking conduction and convection. Conduction and convection both need matter. The near vacuum between the walls has very little, so very little heat can cross the gap in these two ways.

   4Slowing radiation. Radiation can cross a vacuum. To slow it, the wall surfaces that face the gap are often coated with a shiny metal layer, or made of polished steel, which reflects much of the infrared radiation back toward the drink.

   5Where heat still escapes. Heat still leaves, slowly. Most of it escapes through the stopper and through the neck, where the inner and outer walls are joined and heat can be conducted from one wall to the other.

   6Test results (invented for this lesson). 500 mL of water was poured in at 90 °C. In a vacuum flask with its stopper in, the water was 82 °C after 3 hours and 75 °C after 6 hours. In an open ceramic mug in the same 20 °C room, the same amount of water was 40 °C after 1.5 hours.

   7Cold drinks too. The same flask keeps a cold drink cold, because the walls slow heat flowing in just as they slow heat flowing out.

Differentiation Strategies

Assessment Guidance

1. Question 1 of 20 · Multiple Choice

   According to paragraph 2 of the model explanation, what is the order of the parts in each pin stack, from top to bottom?

   AKey pin, then driver pin, then the spring at the bottom BSpring, then driver pin, then key pin at the bottom CDriver pin, then spring, then key pin at the bottom DSpring, then key pin, then driver pin at the bottom

2. Question 2 of 20 · Multiple Choice

   According to paragraph 4 of the model, what does the cam on the back of the plug do?

   AIt pushes the pin stacks down whenever the key is removed. BIt holds the key in the keyway until the door is shut again. CIt lines up each key pin with the shear line as the key slides in. DIt pulls the bolt out of the door frame once the plug turns.

3. Question 3 of 20 · Multiple Choice

   According to the model, what happens when one cut on a wrong key is too deep?

   AThe key pin sits too low, so its driver pin crosses the shear line. BThe key pin is lifted too far, and it crosses into the housing. CThe spring is squeezed so hard that it can no longer push the pins back. DThe driver pin drops out of its hole and falls into the keyway.

4. Question 4 of 20 · Multiple Choice

   The model's sections move from the parts of the lock, to how the pins block it, to how the right key opens it, to why a wrong key fails. Why is this order effective?

   AIt saves the most important idea, the shear line, for the final section. BIt moves from the newest kind of lock to the oldest kind of lock. CEach section uses terms and ideas that earlier sections have explained. DIt places the history of the lock before any of the parts.

5. Question 5 of 20 · Multiple Choice

   In paragraph 5 of the model, what does the transition "Either way" do?

   AIt joins two cases and shows that both lead to the same result. BIt introduces a new section about master keys and their pins. CIt contrasts the right key with a key copied on a machine. DIt signals that the writer is not sure which of the two cases is true.

6. Question 6 of 20 · Multiple Choice

   The research notes describe an example lock with 5 pin stacks, where each key pin can be one of 6 lengths. In theory, how many different keys could this design allow?

   A30 possible keys B11 possible keys C7,776 possible keys D15,625 possible keys

7. Question 7 of 20 · Multiple Choice

   Which sentence in the weak draft "Locks" states something inaccurate about how the lock works?

   A"Some locks have master keys." B"When you put your key in, the pins fall down into the grooves on the key and then the lock opens." C"The key has to be the right one or it won't work." D"Locks are made out of metal."

8. Question 8 of 20 · Multiple Choice

   Which revision of the weak draft's sentence "The springs make it work better" is the most precise and accurate?

   AThe springs are an important part that helps the whole lock to work well. BThe springs make the lock work better and more safely every single day. CThe springs push on the pins, and that is a key part of how it all works. DThe springs push each pin stack down, so the driver pins block the plug.

9. Question 9 of 20 · Multiple Choice

   What do the bold headings in the model, such as "Why a wrong key fails," do for a reader?

   AThey name the question each section answers, so a reader can follow the plan. BThey state the claim of an argument the writer is making about locks. CThey mark the sections that a reader may skip without losing any of the meaning. DThey show which ideas came from the notes and which the writer added.

10. Question 10 of 20 · Multiple Choice

    A student is explaining how a hot-air balloon rises. Which detail is least relevant to that explanation?

    AA burner heats the air inside the balloon's envelope. BHot air is less dense than the cooler air around it. CMany balloon envelopes are made in bright colors. DThe denser outside air pushes the lighter balloon up.

11. Question 11 of 20 · Multiple Choice

    According to the research notes, what does a master pin do?

    AIt locks out every key except the building manager's master key. BIt creates a second gap in a stack, so two different keys can work. CIt replaces the spring at the top of one of the pin stacks. DIt lets the plug turn in both directions instead of one.

12. Question 12 of 20 · Multiple Choice

    A student's explanation of how expansion joints work on a bridge needs a concluding sentence. Which one states the significance instead of only repeating?

    AExpansion joints are the small gaps that are built into a bridge deck. BThat is how expansion joints work, and they are very interesting. CBridges have many important parts, and expansion joints are one. DWithout these gaps, a long deck that swells in summer heat could crack.

13. Question 13 of 20 · Multiple Choice

    Which sentence keeps a formal style and an objective tone?

    AThe key lifts each key pin until its top meets the shear line. BHonestly, the way the key lifts all of the pins is super clever. CYou would be amazed by how the key lifts those tiny pins. DThe key lifts the pins, which is the coolest part by far.

14. Question 14 of 20 · Multiple Choice

    A writer compares the pin stacks to "a row of gates that must all be open at the same time." What does this analogy capture, and where does it fall short?

    AIt captures that the pins are metal, but it misses how small they are. BIt captures that every stack must be right at once, but gates have no height to match. CIt captures the history of the lock, but not how locks are used today. DIt captures the master-key system, but not the ordinary single-key lock.

15. Question 15 of 20 · Short Answer

    In two or three sentences, explain to a reader who has never seen inside a lock what happens when someone pushes in a key with one cut that is too shallow. Use the terms key pin, driver pin and shear line.

    Show model answer

16. Question 16 of 20 · Short Answer

    The four sentences below explain how a rim brake stops a bicycle wheel, but they are out of order. Write them in a logical order, and add one transition word or phrase that shows cause and effect. (a) Friction between the pads and the rim slows the wheel. (b) The rider squeezes the brake lever. (c) The cable pulls the brake arms together, pressing the pads against the rim. (d) Squeezing the lever pulls a cable that runs to the brake.

    Show model answer

17. Question 17 of 20 · Short Answer

    Rewrite this sentence from the weak draft so that it is accurate and precise: "A lock has a big pin inside it that holds it shut." Use the research notes.

    Show model answer

18. Question 18 of 20 · Short Answer

    The model ends with an implication about a sticking key. Write a different concluding sentence for the model that states another implication or the significance of the design.

    Show model answer

19. Question 19 of 20 · Short Answer

    Which two of the ten research notes would you leave out of an explanation of how an ordinary front-door lock opens, and why? Then name one note that must stay, and explain why the explanation would fail without it.

    Show model answer

20. Question 20 of 20 · Short Answer

    Use the master-key note (paragraph 9 of the research notes) to explain, in two or three sentences, why a master-keyed lock may open for more keys than its owner intends. Suppose every one of the 5 stacks in the example lock has a master pin.

    Show model answer

These are the grade-level standards that carry anchor CCRA.W.2 in grades 6-12, plus closely related anchors.

Standard text: Common Core State Standards for English Language Arts & Literacy. © Copyright 2010. National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved.