Insolation & The Path of the Sun

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Objective

SWBAT define insolation and identify latitude and season as the two (2) factors that affect the intensity of insolation | SWBAT diagram the path of the Sun on a world map at different points of the year

Big Idea

Students use altitude diagrams to chart out the path of the Sun at different times of the year and at different latitudes in this lesson!

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: 4.6 - Insolation & Zenith (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: 4.6 - Insolation & Zenith [Entire Lesson]. 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.]

In this lesson, students will focus on latitude and season as the two primary factors that affect the intensity of insulation, and then will diagram the path of the Sun by creating altitude diagrams at different positions on the Earth's surface. This is a logical extension of a previous lesson (linked here), where instead of analyzing and observing the path of the Sun, they're actually creating the physical altitude diagrams. 

Do Now & Introduction

10 minutes

Students come in silently and complete the (attached) Do Now. In this case, the Do Now is a review of material from Unit 3 (Geologic History), in preparation for the upcoming interim assessment. 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).

Altitude Diagrams

20 minutes

The lesson starts with exposing a popular student misconception - that the seasons are caused by Earth's distance from the Sun. As an introductory piece, I pose the question on the first page of the Introduction resource to students, and have them think about it for a few seconds. Many of them have figured out the answer from previous lessons, but there are still many students who erroneously choose the summer. In fact, Earth is technically closest during its orbit during the Northern Hemisphere's winter!

From there, we use this as a natural transition to discuss the tilt of the Earth as 23.5 degrees. We then explore that this tilt plays out by affecting the intensity of insolation received both at different seasons (as in, there is naturally stronger insolation received during the summer months than the winter months) and as a function of latitude (the equatorial regions of Earth receive the most direct and high-angle rays of the Sun, while the polar rays receive mostly low-angle, less intense insolation). 

We continue the discussion by looking at the map on the bottom page of the first page of the Introduction resource. We then re-visit an earlier concept, the zenith, and label where the zenith would occur at different points of the year (most notably, the Equinoxes/Solstices) [Note: Please refer to embedded comments in the Word document resource attached in the 'Lesson Introduction' for specific questions/CFUs and information that students receive here].

Once we've finished with detailing insolation's intensity changing as a result of both latitude and season, we then transition into the (tricky) Altitude Diagrams. Generally, there are three (3) altitude diagrams to tackle, and I approach these in a traditional lesson format, as an "I Do, We Do, You Do." I'll do the first one on the ELMO with student support, they'll try the second one in more of a group/guided practice content where they'll be able to review their work with me, and the third one is one where they'll get the chance to try it independently. I should note here that the North Pole one is particularly challenging, and students generally need a good hint or two in thinking about getting started. 

For the first altitude diagram, the path of the Sun in New York State (NYS), I first point their attention to a website to help illustrate the concept (below is a quick embedded video of some features of the website for you to try out).

Using the website, I briefly explain how the difference between the summer solstice and fall equinox is always 23.5 degrees, regardless of position on the Earth's surface. Similarly, the difference between fall equinox and winter solstice is always 23.5 degrees. Put more simply, the altitude of the Sun always changes by 47 degrees throughout the year, regardless of positioning. We then illustrate this concept in NYS. Once they know the height of either an equinox or solstice, they can figure out the altitude of every other path by adding or subtracting 23.5 degrees [Note: The vernal/autumnal equinoxes are always at the same altitude, and the winter is always 23.5 degrees below that, while the summer solstice is always 23.5 degrees above that, at least in the Northern Hemisphere. So at 41 degrees North latitude, if I know the Equinox has an altitude of 49 degrees, I can easily figure out the altitude of the summer and winter solstices].

I do the first one (NYS), as stated above, mostly as an "I do," and follow by asking students to do the increasingly complex ones at the Equator and the North Pole. If it looks like they're struggling, Ill usually return to the website to show the the path of the Sun on the Equinox at the Equator, or at the North Pole to give them the appropriate visual. Then, after giving them the chance to try these out (takes about 10 minutes total), I'll show them an exemplar that I've previously made, with the altitude diagrams complete for the final two, giving students a chance to correct and edit their work. 

Practice

20 minutes

The Practice section in this lesson is, like the vast majority of questions found in all of my classwork and homework, is 100% Regents-based. All of the questions come from prior Regents examinations. Likewise, as I try to generally do with all of my lessons, the questions are mostly organized to get increasingly more difficult and increase in complexity, which is why the harder questions tend to come toward the end. For whatever reason, I've found that many students struggle with this content - they mix up the shadow lengths, the inverse relationships, all that stuff. The best way I've found to combat this is to give them the chance to identify and correct their mistakes in questions of this type, which is why this section is a little extended as per my usual lessons. 

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) 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 where the vertical ray falls on the respective Equinoxes/Solstices, 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.