Tecnología lítica como ritmo de interacción social

The solar cooker project emphasizes problem solving for a global issue involving cooking fuel and health concerns. This project can be deployed in ten days or up to four weeks depending on the learning outcomes or level of depth desired. The project consists of multiple stages. For the first stage, the students, working in pairs or occasionally in threes, watch a very brief slide show where the students are introduced to the problems associated with cooking in countries whose population has minimal economic means and insufficient power supply. Briefly the students are introduced to the following:

Over one-third of the world’s population relies on wood, dried animal dung, crop residues, or charcoal for domestic energy needs including indoor cooking. Many problems are related to this issue: the problem of long journeys to collect fuel (which leads to missed schooling and further eroding their economic status), excess time spent cooking (mostly by the women), the health issues associated with smoke inhalation (1.6 million die each year from cooking fuel smoke), etc.

The problem statement is then given to the students: “What can be done to address this issue and thereby alleviate extreme poverty, improve education, promote gender equality, reduce child mortality, improve health,

and promote environmental sustainability?”. Depending on the duration of the project, the students are given either 24 hours or one week to prepare a response which includes a list of possible solutions and expanded detail on the best solution in the list. During the subsequent class period, the students and instructor discuss some of the solutions and whether or not they solve the problem. As it turns out, there is only one good solution: a solar cooker. Each team is then tasked to design, build, and test a solar oven, which must be able to purify water and cook food for an individual family or small group. Note that for testing purposes, the designs should be able to contain a dial-gage (oven) thermometer inside of a small cooking pan placed inside of a sealed cooking bag. Each team is required to submit:

 evidence that their oven meets specifications

 a functional prototype of the oven

 originally created design specifications and plans that allow someone to construct a replica oven

 detailed cost to reproduce the oven if it was mass produced by hand using readily available materials

 a deployment plan for which region/country will receive the ovens.

 a final report conforming to specific guidelines

The teams are allowed to use designs that are readily available on the internet at sites such as

solarcooking.wikia.com/wiki/Category:Solar_cooker_plans and www.re-energy.ca/docs/solaroven-cp.pdf. Examples of solar ovens are shown in Figure 3.

Figure 3. Examples of student teams’ solar ovens. The students do not work in teams of four as implied by the photos. It is also possible to frame the project with a real-world business scenario. An example of a problem statement follows:

A non-profit organization (The Carpenter Foundation) is awarding two $100,000 grants for the best solar oven design that can be easily replicated and distributed in third-world nations. Your design team is challenged with winning that award and improving living conditions in a country/region of your choice. Each team will create a 15-minute presentation using PowerPoint to “sell” their design. The presentation should include a distribution plan (including country or region), and details on how the money will be spent (e.g., project overhead, training, production, shipping, etc.).

Besides practice of the engineering design process and professional skills, learning objectives can include topics of sustainability and ethical obligations of engineers. The students also gain some experience with technical skill development. After the ovens have been tested a presentation detailing the modes of heat transfer as related to the solar cookers is reviewed and discussed. This information can be supplied before the design process begins or the students can be allowed their own self-discovery (as is typical in project-based learning).

Unless the students are designing a new, original cooker, there are many steps of the engineering design process that are unnecessary, so the goal here is not to use each step of the process. Instead the students need to perform thorough research to carefully pick the best design (i.e., best use of the modes of heat transfer) that can be built within the limited time frame. They also must practice careful construction techniques to maximize reflection and optimize direction to ensure proper heat absorption. (A well-built solar oven made mostly of aluminum foil and cardboard will easily reach temperatures over 230ºC (450ºF) on a clear sunny day, even in

cold winter weather.) Therefore the results of teamwork, using the computer for research, and engineering design steps 2 through 4 are pertinent. Assessment data is only available for the 10 day version of this project, wherein oral and written communication results were not applicable. Table 2 reveals the engineering design steps 2 through 4 at a level of 4 or higher, as is desired for a project in the middle of the academic term. Despite limited knowledge of heat transfer, the students attempted to use scientific and engineering principles in their design. Also from Table 2, the students appear to be achieving a significant level of teamwork, and are mostly implementing the computer as a research tool for their design, albeit with a high standard deviation. It has been concluded that some students leave the computer research to their teammate(s).

Table 2. Students’ ratings of statements after completion of the Solar Cooker Project

Skill Average Median

Standard deviation

2. Conceptualize various options 3.94 4 1.05

3. Design using sound scientific and engineering principles 3.92 4 0.93

4. Build, fabricate, or model 4.44 5 0.82

Importance of teamwork for this project. 3.97 4 0.90

Practiced teamwork 4.38 5 1.18

Used the computer (not including note-taking or communication such as email) as a tool for the design, testing, and/or, evaluation

3.46 4 1.48