Wednesday, March 26, 2008

Making and Using a Sextant

I like to integrate our science with history studies and here is an example of how I've done that!

Due to our current Renaissance studies of explorers sailing around the world, I posed the question, "How tall is the house?" Thus beggan his newest science objective.  Our literature and history books have been interspersed by sailors who sight the stars for navigation.  Surely, he could sight the top of our house? ;)

On Monday, I handed my son a printout on how to build a sextant. Then he practiced with a height he could measure, our tall bookcase in the schoolroom.  He made a few mistakes at first.  Undaunted, the gears of his brain whirled while he adjusted his calculations and figured out how to correctly assess height.  He got to apply all of the math skills he's been learning.  He's currently doing geometry and learned a new skill for this lesson, how to use tangent.  This makes tangent quite useful, a handy skill when he officially learns it in his math book!  He'll have a wonderful ah-ha! moment when he meets tangent again in math class! ;) 

Then he was ready to tackle the house! Here he is sighting the chimney through a straw taped to the protractor. 

 I stood at his side, reading the protractor for him, telling him when the plumb line measured 45 degrees.  He couldn't keep the chimney in sight, so he decided to measure to the top of the eaves.  He walked toward the house, sighting with his sextant, until I told him that I saw the plumb line reach 45 degrees.  At that point he stopped and we got the measuring tape out. 

 I walked the end of the measuring tape to the edge of the house, while he held onto the bulk of it, measuring the distance from the house to where he stood.  That was between 16-17'.  Then he computed his calculations. Apparently the eaves are 21'5" from the ground. 

Next questions: What's our latitude?  Can he sight Polaris tonight? 
This is a great science activity to do with any historical era where the student is learning about sailors! Even in the modern era, when fancy equipment fails, navigators have resorted to this technique! 


  1. SongOfTheSagebrushMarch 26, 2008 at 5:45 AM

    I love it!


  2. my kids tried to use a tangent when we were studying the explorers, but stuck to simple things like the book case and the ceiling. How great your son is so inquisitive.

  3. Looks like a cool project!

    I would love to hear about those dreams sometimes...

    And, I just wanted you to know, my mom, Indiana Mimi, sometimes visits your blog just to look at the picture you have at the top. She loves it! I saw her on here one time, and I didn't know she read any other blogs but mine and mine sister's.

  4. MayTheyBeMightyMenMarch 27, 2008 at 6:31 AM

    I loved reading about this, and I vaguely remember doing a similar thing in school when I was in fourth grade. I believe we were sighting an oak tree that day. ;')

    I have a feeling my son would love this kind of project. Of course, it's not something that will be presented this year for him, and I guess I'm okay with that. We'll work on being solid with what he needs to know now and get to love that first.

  5. Wow! Very, very cool! Give him kudos from me. Your ds and my 8 year old son are two peas in a pod. I'm going to remember this for when Gabe is older!