MEFW Project 2061 II

From Mainsequence

Jump to: navigation, search


Contents

Introduction

This is a second page of notes on Project 2061, the AAAS attempt to semi-formally describe the growth of scientific understanding in school-age children, particularly K12 in the United States. The first page of notes is here. This page treats two of the strand maps as narrative source material, an unfortunate "linearization" that is nevertheless necessary in this medium (wiki page).


Part I of IV: Data sample

From the Energy Flow Workshop we have


Temperature on South Boulder Creek in early March 2008: 3 Air temps and one averaged water temp (6 sensors)


this data. There are four signals: Three temp sensors are in "air" (two at the bases of trees, one three feet off the ground in the cleft of a stump (the red line)). These are on either side of South Boulder Creek where six temp sensors are averaged to give the green signal. All 9 sensors (OneWire iButton Thermochrons) are within about 50 meters of one another.

Part II of IV: Flow of Energy in Ecosystems

Living things transform energy; plants trap light energy to assemble food molecules, and consuming organisms oxidize that food for energy. Knowledge of these transformations and of the irreversible flow of energy from sunlight, through the food web, and back into the environment as heat are a critical part of students' understanding of ecosystems. This map displays the progression of benchmarks about energy in living things, plants making food, and food webs.

[...]

The term "energy" is used in two benchmarks in [grades] 3--5, and that is certainly before students can truly understand the concept. But the simple notion of energy as "something that makes things go or grow" is adequate at this stage, and con contribute to their later, more advanced understanding of energy.

Getting students to understand energy transformations in living systems requires that they grasp the fairly sophisticated concept that changes in configruation of atoms in molecules absorb or release energy. [...] This benchmark is essential for understanding the linkage of matter and energy.

Atlas of Scientific Literacy, Volume I page 78


Struggling to define energy has come up many times in the workshop. A short working expression is a good idea; we tend to resort to listing examples but I don't think this is adequate in service of the students. I will continue to quote from the same page of the Atlas, focusing on the thesis and hence omit the citations. Please do refer to the source and the citations for a real study of this topic. The sketch-quote given here is to indicate pitfalls, patterns of inferrence by students working with this subject.


Students' meanings for "energy" both before and after traditional instruction are considerably different from its scientific meaning. In particular, students believe energy is associated only with humans or movement, is a fuel-like quantity which is used up, or is something that makes things happen and is expended in the process. Students rarely think energy is measurable and quantifiable (Solomon, 1985; Watts, 1983a).


(See the discussion of Owen's morning visit to the pool hall.)


Although students typically hold these meanings for energy at all ages, upper elementary school students tend to associate energy only with living things, in particular with growing, fitness, exercise, and food.

Middle- and high-school students tend to think that energy transformations involve only one form of energy at a time. Although they develop some skill in identifying different forms of energy, in most cases their descriptions of energy change focus only on forms that have perceivable effects. The transformation of motion to heat seems to be difficult for students to accept, especially in cases with no obvious temperature increase. Finally, it may not be clear to students that some forms of energy, such as light, sound, and chemical energy, can be used to make things happen.


Introducing "energy leaking from one form to another" at the outset: Perhaps a good working idea.


Some students of all ages have difficulty in identifying the sources of energy for plants and also for animals. Students tend to confuse energy and other concepts such as food, force, and temperature.


This suggests that we can kill two misconceptions with one stone: Heat is a form of energy (not temperature) but temperature is a means of measuring heat, of assigning a number or quantity to energy in this particular form.


As a result, students may not appreciate the uniqueness and importance of energy conversion processes like respiration and photosynthesis. Although specially designed instruction does help students correct their understanding about energy exchanges, some difficulties remain. Careful coordination between The Physical Setting and The Living Environment benchmarks about conservation of matter and energy and the nature of energy may help alleviate these difficulties.


Alright, so there we arguably have some validation for placing { stars - student - earth } in a context web by suggesting careful integration of the world of life and the physical world. It's probably worth mentioning that there is no point in becoming discouraged over the enormity of the subject. Rather I'd suggest placing confidence in the subjects; at any level of learning there is always something new. For example the students fell sideways into a discussion of water circulation during Session 14. What didn't come up during this discussion were these two ideas:


  • Avogadro's number in a drinking glass: We have so many water molecules that (given adequate mixing mechanisms such as evaporation) in a short time interval we find ourselves sharing water with everyone on earth.
  • Black smoker restrictions on abiogenesis time: (I think this is courtesy of Stanley Miller) If life arose in the world's oceans, consider the rate at which black smokers boil water. It would seem that every drop of water in the ocean can, roughly speaking, expect to 'get boiled' every ten million years. Hence you have ten million years to evolve life with sufficient motility to swim away and not get boiled!


Part III of IV: Returning to the plot above

Visit this page of the wiki for a more comprehensive look at the temperature and error signals.


The chart above shows air temp for 3 different sensors and water temp averaging 6 sensors in South Boulder Creek for three days in March 2008. The full record is 14 days long. Below is a first listing of some inferences about the physical setting of the ecosystem. I should mention that the averaged water temperature also appears quite smooth for each of the six source sensors; this is not an artifact of averaging. A more complete analysis will be given in the Session pages for the workshop.


  • The water temperature goes through a diurnal cycle that lags behind the air temperature.
    • We can infer that it takes longer for "daytime heat energy" to enter the stream water than it does for the ground.
  • The stream temperature changes in a smooth way whereas the air temperatures change in a jagged manner.
  • The stream temperature tends to reach a minimum around 8 am, so it continues to lose heat over the course of the night.
  • During the early morning hours of March 6 the stream seems to have hit a minimum temperature of 31.5 degrees or so (where we assume the stream did not turn to ice so the discrepancy with 32 degrees might be due to inaccuracy in the thermochrons).
  • The stream frequently approaches the freezing point of water at its coldest point in the daily temperature cycle.
  • The stream regularly reaches its maximum daily temperature at about 4 pm.
  • The stream undergoes daily temperature variations or swings of between 10 and 20 degrees Fahrenheit.
  • The stream temperature cycle seems to rise for 8 hours (between 8 am and 4 pm) and fall more gradually for 16 hours.
  • The "Air Stump" sensor three feet off the ground (in contrast to the other two air sensors which were at ground level) is more susceptible to cooling at night.
    • This might imply a "thermal blanket" or heat-energy reservoir effect close to the ground.
  • The "Air Tree North" sensor warms up first with a pronounced rise in temperature at around 7 am, presumably near sunrise (additional information needed).
    • The stream tends to enter its daily warming phase an hour later than the ground.
  • The air temperature sensor high variability might be related to changes in cloud cover or wind.
    • It would be helpful to have a nearby temperature record as an independent source of information.
  • Since the red, black, and blue temperature records for the air temp sensors are highly variable, we can conclude that any single-location temperature measurement is likely to be seeing a great deal of "microclimate" noise on a scale of tens of degrees Fahrenheit.
  • Air Tree South and Air Tree North signals track one another well between 2 pm and 7 am. After 7 am Air Tree North experiences a period of higher temperature. ** It is quite possible that the Air Tree North sensor had direct exposure to early sunlight coming from the east.
    • This variability in air temperature suggests creating a 3D array of sensors to better capture what causes may be operating.
    • Temperature records for these days will also suggest if sunlight exposure is responsible for some of the high temperatures recorded.



Part IV of IV: The Atlas describes The Physical Setting

We have the following Atlas Volume I pages in Chapter 4 on The Physical Setting (of Life, the Universe, and Everything):

  • The Universe:
    • Gravity
    • Solar System
    • Stars (!)
    • Galaxies and the Universe
  • Processes that shape the Earth:
    • Changes in the Earth's Surface
    • Plate tectonics
  • Structure of Matter:
    • Atoms and molecules
    • Conservation of matter
    • States of matter
    • Chemical reactions
  • Motion:
    • Laws of motion
    • Waves


There is undoubtedly more to this in Volume II of the Atlas.

Retrieved from "http://robfatland.net/mainsequence/index.php?title=MEFW_Project_2061_II"
Personal tools