Humidity

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Objective

SWBAT define humidity, relative humidity, and dew point and identify the relationship between humidity and temperature

Big Idea

Students discover that as air heats up, it can hold more water vapor, and that dew point is the temperature at which the air is fully saturated. Students also learn about how changes in air temperature cause humidity (and dew point) to increase or decrease

Lesson Introduction

[Note: For embedded comments, checks for understanding (CFUs), and key additional information on transitions and key parts of the lesson not necessarily included in the below narrative, please go to the comments in the following document: 5.2 - Humidity (Whole Lesson w/comments). Additionally, if you would like all of the resources together in a PDF document, that can be accessed as a complete resource here: 5.2 - Humidity [Whole Lesson][PDF]. Finally, students may need their Earth Science Reference Tables [ESRT] for parts of the lesson (a document used widely in the New York State Earth Science Regents course) as well.]

Students get the chance to study humidity, relative humidity, and dew point and analyze how it relates to the air temperature in the atmosphere. We watch a brief video that introduces and explains the "stickiness" of humidity and then break down some scientific texts to figure out how warmer air can hold more water.

Do Now & Objective(s)

10 minutes

Students come in silently and complete the (attached) Do Now. In this case, the Do Now is a review of material and remediation standards from the unit on Insolation (Unit 4) that the entire grade tended to struggle with. After time expires (anywhere from 2-4 minutes depending on the type of Do Now and number of questions), we collectively go over the responses (usually involving a series of cold calls and/or volunteers), before I call on a student and ask them to read the objective out loud to start the lesson.

As a general note, the Do Now serves a few purposes:

  1. It serves as a general review of the previous day's material; (again, this is a bit different, as they are reviewing for the quarterly Interim Assessment)
  2. It is a re-activation of student knowledge to get them back into "student mode" and get them thinking about science after transitioning from another content area or alternate class;
  3. as a strategy for reviewing material students have struggled with (for example, using this as a focused review for material that they have struggled with on unit assessments or recent quizzes); and,
  4. It is an efficient and established routine for entering the classroom that is repeated each day with fidelity (I never let students enter the classroom talking. While it may seem potentially severe to have students enter silently each day, this is both a school wide expectation and a key component of my classroom. In many respects, I find that students readily enjoy the focus that starting with a quiet classrooms brings each day).

Introduction & Video

15 minutes

We start the lesson with the Introduction & Video, in which students use a Cornell Notes template to take notes from a video on Humidity from the BrainPop! educational video site (Note: The video is behind a pay wall, although many schools and districts have accounts already. Check with your administrators or district representatives if you're not sure!). The video itself is only about two (2) minutes in length, but it very effectively gives students the information they need at an appropriate level of rigor for early high-school Earth Science. Many videos on humidity either don't get deep enough or get really technical in a way that's too far for most of my students. I like this video because of it's interesting visuals, simple explanations, and dense information (Also, see the Reflection in this section on Cornell Notes for more context here).

We use the video to take notes (it may be necessary to play it through twice) before I ask students to summarize their key points on the next page. Following this, I have students turn to the text on humidity in the Introduction & Video resource, which very simply explains the relationship between humidity and temperature. I have students take the opportunity to read this with a partner and answer the four (4) associated questions on the next page. After giving them 7-8 minutes to complete this, we'll collectively review the answers before jumping into the practice section of the lesson. 

Text

15 minutes

After the video, we jump into the Text to help us further clear up the topic of humidity. This is an information and vocabulary-dense section, so I structured the questions on the second page of the Text to directly address the notions of vocabulary. Often, the Regents will do things like phrase questions using synonyms or long-winded vocabulary (saying something to the effect of "What is the percent saturation of water vapor in the air?" instead of something more straightforward like "What is the relative humidity?"). I've found that it's important for students to know the difference between humidity (measured quantitatively as a g or kg/cubic meter of air) and relative humidity (also measured quantitatively, but as a percentage), and dew point is a whole other variable that can be confusing, but is relatively simple if they know how to structure a definition using humidity (dew point is just the temperature when the relative humidity is 100%). 

To get at this idea a bit better, I structured the text to be vocabulary-intensive. Students are to take the time in partners to read through the information carefully, and then answer the associated questions on the next page in complete sentences. Three out of the four questions are directly about the newly learned vocabulary, and the fourth (#2) addresses the super important relationship between temperature and humidity. After giving students about 5-6 minutes to read and answer the questions, we come back together to go over the information together. 

Practice

15 minutes

The Practice section in this lesson is, unlike the vast majority of questions found in all of my classwork and homework, is not 100% Regents-based. In this context of being such a basic and introductory lesson, while there are a few Regents-based problems here, I really wanted to take the time to emphasize the distinction between heat transfer with some questions applying their newfound knowledge (confusing and alternating the definitions is a frequent error seen with questions of this type). I think it's only important to emphasize the key points of the lesson on a basic level, especially since the lesson itself is so information-dense with the amount of material covered in a single period. 

In terms of student work habits, I tend to sometimes make this decision in the moment, and as a response of what I know about the students and how they're processing the material on, but I'll either ask them to work independently, in partners, or (sometimes) give them the option. Usually, before starting practice, we tend to go over some steps for self-help ("What should you do if you're stuck?"), and I might reference a previously used multiple-choice or free response strategy in order to build their skills while simultaneously learning content (as an example - one popular one we always use - "If you aren't sure what the right answer is, see if you can eliminate some wrong answer choices"). I tend to circulate for compliance and then hone in on specific students while they're doing this. 

After about 10 minutes, we go over their responses. Students who finish early are encouraged to work on the exit ticket (resource below) and double-check their responses. We use a combination of strategies (active voting, cold calling, popsicle sticks, volunteers - here's a video of me doing just that) to go over the responses, where students correct their work and ask any clarifying questions. 

Exit Ticket & Closing

5 minutes

In the last few minutes of class, I have students complete the daily Exit Ticket. For the sake of time, I have students grade them communally, with a key emphasis on particular questions and items that hit on the key ideas of the lesson (Note: This usually manifests as students self-grading, or having students do a "trade and grade" with their table partners). After students grade their exit tickets, they usually pass them in (so that I can analyze them) and track their exit ticket scores on a unit Exit Ticket Tracker. 

After students take a few seconds to track their scores, we usually wrap up in a similar way. I give students time to pack up their belongings, and I end the class at the objective, which is posted on the whiteboard, and ask students two questions:

  1. Do you feel that you mastered the objective for the day?
  2. Can you reiterate one thing you learned about (in this case, information on the relationship between temperature and humidity, etc.)?

Once I take 2-3 individual responses (sometimes I'll ask for a binary "thumbs up/thumbs down" or something similar), I have students leave once the bell rings.