Sea Floor Spreading (Day 2/2)

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SWBAT create a graph modeling the process of sea-floor spreading in continental drift (and rock formation)

Big Idea

In this lesson, students construct a graphical model of the ocean floor (the Atlantic Ocean), describing its physical features, identifying its plate motion and associated characteristics, and diagraming its magnetic polarity

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: Sea Floor Spreading (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: Sea Floor Spreading (Entire Lesson) [PDF Version]. 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.]
This is the continuation of the previous day's lesson (link here) on Sea Floor Spreading. During this lesson, students take additional time to complete the graph that they started on Day 1, and then do some post-graph analysis before taking an exit ticket/daily summative assessment. 


Do Now & Introduction

10 minutes

Given that this lesson is a continuation from the previous day, there is no traditional 'Do Now,' as there is in most of my other lessons. Students still enter the same way - they quietly get to their seats and take out their materials from yesterday (if you wanted to collect their materials for safe-keeping, I would either hand it out as they enter the room, or have it readily and easily accessible for them as they go to their seats). Once they have their materials out, they can either immediately continue graphing (if they didn't finish yesterday) or start on the post-graph analysis section, which has them utilize their graph to provide additional information on sea-floor spreading. 


30 minutes

Again, as noted in yesterday's lesson, they key reason that this lesson is actually designed to be taught over two days is because of the extensive time that students need to actually Graph the sea floor profile, and then begin the post-graph analysis. Once students have the hang of it (this should have been gone over yesterday, although individual students might need some help as you circulate), I just give them the time to individually (and carefully!) plot out the points in their profiles. They can use a ruler or a straight-edge to connect the points on the line (you can pass these out at the beginning of the lesson if students don't already have them), but in circulating, pay careful attention to the correctness of their axes and to how faithfully they're plotting the points. Due to the nature of it being a negative axes (and kind of an odd graph that they're not really used to), I need to be extra vigilant for mistakes here. 

Also, if students finish early, encourage them to go onto the next section, the post-graph analysis (see below for resource). 

Post-Graph Analysis

20 minutes

In my opinion, the Post Graph Analysis is the most important part of the two-day lesson. All the graphing stuff is helpful in terms of getting them to practice their graphing skills and think critically about how best to plot an ocean floor profile, but this is actually where they begin to illustrate the idea of sea floor spreading by marking up their graphs. 

Using the resource, I have them answer the questions in complete sentences, using their plotted graphs, and notes, as supporting evidence. In terms of how you would lead this, I generally do it by the feel of the class. This year, I have a class that has students who struggle a bit more academically, so when I frame this section for them, I model the first part of each step and then leave my semi-completed graph on the ELMO for students to reference as needed. For my other classes, which tend to be a little more advanced, I usually back off a bit and let them complete steps 1-4 in their own way. Sometimes, it might be acceptable to have them reference a partner for hep if you're getting individualized questions. For reference, you can find a completed (although messy) graph here: Completed Graph

Exit Ticket & Closing

10 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. This is the time I also pass out the nightly Homework assignment. 

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, the process of sea floor spreading, 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.