Latitude and longitude

Although hide and seek had used smartphones to obtain GPS coordinates, for the laboratory I returned to using handheld GPS receivers. 

The class began at E 158° 09.600' on a line of latitude that I thought might just miss the corner of the B building. The specific latitude varied and by receiver and went unrecorded. 

The weather was, for the first time in a number of terms, cooperative with relatively dry ground conditions. 

Sharla and Ashlen heading East

Jarret takes a reading at 30 meters

Ashlen takes a reading at 30 meters

Serjean joined 8:00 on the left, Athina Viola on the right records data 

The Tripltek tablet provided conversions for the measuring wheel. This track put the wheel up on the bend out around 90 meters.

Taking a reading under the Terminalia catappa tree

The class hit the fence just shy of 180 meters, so I ran up the into the acute corner. This required a slight deviation north of due east. 

I hit 180 meters exactly at the cement in the corner.

Serjean records data in the corner

Sharla and Ashlen record their 180 meter data

The Tripltek running GPS Essentials located the corner at these coordinates

In the afternoon I opted to start where I wanted to end in terms of latitude at N 06° 54.573', just to the north of the morning start. 

Billy, Milain, Shane, and Fiji get set up at the new North location

Ivan

Kaylem, Thevonna, Rizal, Harvey, Melina, Billy

Jenna, Fiji, and Ivan take longitude readings along the line of latitude.

This route would eventually prove four meters short of 180. Perhaps a return to a start at E 158° 09.500' should be re-examined.

The weather continued to hold for us.

The northern route took us over an area that is typically very soft, wet, and muddy. Only the weather made this route passable. 

Thevonna

The route did give me a clear target for the endpoint.

The usually soft area of swampy mud is behind Billy. 

Much to my surprise we did not reach 180 meters by the time we reached the acute corner.

At 576 feet we had only reached 175.565 meters. 

The table didn't include conversions below 180 meters. 

The data is from the 8:00 class except for the 176 meter mark which was from the 11:00 session. 176 works well too, and the data is sufficient to establish a linear relationship. Walking back to E 158° 09.500' has its downsides too. The loss of being able to reach 0.100 arcminutes may have a negative impact, but again this term I focused on:

• Is there a mathematical relationship between arcminutes and meters? 
• Is that relationship linear?
• If linear, then the slope is a conversion factor between arcminutes and meters.
• The conversion factor can then tell us how close to a location the last decimal place can put one (setting aside error in the GPS reading). 

I again did not try to extrapolate to the circumference of the Earth because I wanted to keep the focus on the ability of GPS to very precisely locate a position on the planet. This ties the lab back into the Wednesday hide and seek. The boards were not captured this term but were arranged along the lines of last term.

Post-script: the boards were not erased as of Friday:

The Friday wrap up activity was a set of three videos on traditional navigation.