Showing posts from September, 2011

When the mode is not the mode

When a number appears more than once in a list and there is a multi-way tie at that frequency, the mode function in spreadsheets malfunctions and produces an answer when the answer should be "no mode." There is no single mode.

For as long as I have used spreadsheets, spreadsheet software will always pick a number from the multi-way tie and report that number as the mode. This would not necessarily be problematic, however different spreadsheets produce different results.

In a Lubuntu 11.04 Natty Narwhal equipped computer laboratory, the students have access to and are free to choose from Calc, Gnumeric, or Google Docs.

Given the data 2000, 640, 256, 128, 128, 1000, 512, 512, 384, 256; chooses 128 regardless of the sort order. Google Docs chooses 512 regardless of the sort order. And Gnumeric chooses a member of the tie that changes with the sort order.

Note that technically all of the spreadsheets cited are incorrect. The correct answer for th…

Run to The Village

I was asked what a District Three fun run might look like if the run started at The Village and ended at Nett Elementary school. Would that be five kilometers? The discussion also looked at transportation issues, which raised the possibility of a Nett Elementary five kilometer out-and-back.

Having been unable to get a run in during last week, I took the opportunity to get in a run and gather some data at the same time.

Nett Elementary is three kilometers from Dolihner via Pohnpei campus:

A five kilometer out-and-back would turn around at the house seen below. One could theoretically try to place the turn-around exactly at 2.5 kilometers, but that location is simply a banana tree next to the road.

For road race distances the route should not be short, an extra 140 meters ensures that the route is indeed at least five kilometers given the GPS unit position error of up to 10 meters.

A more logical District 3 turn-around would be this bridge on the Nett-U border. That would generate a 5.8…

Lubuntu LXDE

I spend a good deal of time reminding my students in the computer laboratory to use alt-tab to try to recover lost windows. The new Unity desk top in Ubuntu Natty Narwhal 11.04 is simply confusing for the students. The launcher is an unusual metaphor in this virtually Mac-less nation.

The computer lab computers being older 512 Mb RAM machines, there are also problems with the resource intensive Unity desk top. After a hour of running, the launcher will often fail to auto-hide for Calc.

For other reasons, I stumbled upon Lubuntu LXDE. Test runs on two computers in my office show LXDE to be faster and more responsive than Unity. The real plus, however, is that students were able to instantly understand and use the desk top without any assistance. With the rest of the campus running Windows Vista and Windows 7, the similarity of LXDE is a real plus.

I am more than pleased that Lubuntu will become a full sibling to the other Ubuntu distributions with 11.10. With all t…

RipStik Pairs Racing 2024 Brisbane Olympics

In preparation for the introduction of caster boarding to the 2012 Olympics in Brisbane, the kids are practicing their racing skills, both pairs and solo work.

 In the female pairs competition, these two are well ahead of the rest of the planet. Solo riders are globally distributed, but pairs riders are far less common. Teamwork and rhythm and a keen sense of pairs balance are critical assets in this event.

The pairs riders are off on a racing loop of the RipStik track, also known as Pohnpei International Airport parking lot near sundown. With only one plane per day near midday, the lot is all but deserted as the sun sets.
The male pair riders have established a strong lead on the turn into the back stretch.
Foot placement and positioning is another critical element in this sport. Years of practice are required just to get to this level of togetherness.
Note the parallel front foot stance for the female pairs. This is essential to remaining upright and moving forward.
The old man demo…

Exploring momentum

Laboratory 042 was following the constructivist variation piloted spring 2011. I ran the set-up in the same manner in which I set-up last spring and last summer. I first asked the students to predict the result prior to any marble collisions. Then I released one marble on a shallow ramp. The marble rolled down and collided with a line of five marbles of roughly equivalent mass.

 Ariel presents results as MacArthur and Alden watch
I repeat this with two, three, four, five, and even six inbound marbles. For the latter cases I shift the focus to the "break-away group" retaining the inbound number as the released marbles also tend to continue on post-impact and eventually off the ramp.

Once the students grasped "marbles in" equals "marbles out" then I focused on the penultimate marble.

How does the penultimate marble "know" whether it should stay or go? How does the penultimate marble in the line "keep count" of the number of inbound marble…



Arc of a ball and acceleration of gravity

Exercise 031, the mapping of the parabolic arc of a ball, was modified again this term. I wanted more data points than the exercise traditionally generates. Last fall I hit upon the idea of keeping the arc wholly on the white board and using an army of students with markers to capture the ball arc data points.

I repeated this again during the spring term, although the marks were not as accurate as I might have hoped. I also did not leave enough time to explain the theoretic function, how to enter it into a third column in a spread sheet, and then graph the actual data and the theoretic curve on the same chart in a spreadsheet. Spring term I had 34 students, checking their RipStik accelertion homework took longer than usual. Although the homework check uses time, it also provides a valuable opportunity to see what each and every student is able to do and not do.

Fall 2011 the homework check took time and I again did not have the time I would have liked to introduce the …

Lycophyte and monilophyte presentations

Students in SC/SS 115 Ethnobotany gave presentations on the botany and local names of cyanobacteria, lycophytes, and monilophytes.
 Pauleen covering the life cycle of Lycopodiella cernua

Jeanette lectures on the life cycle of a fern.
Trisha was part of a team that covered fern morphology.

The following Thursday was our visit to the Pohnpei Traditional plants garden. There the students were given an introduction to healing plants and a tour of the garden.
Barnson, Maylanda, and Pauleen liten to the presentation.

Con-ray on the tour observing a climbing Pandanus.
 Maylanda, Pauleen, and Noeleen in the front. Verginia, Trisha, Christlynn, RinaRuth, Lisa in the second row. Claralyn, Neelma, Jeanette on the third tier.