The case that is readily made for outdoor classrooms is that they provide hands on opportunities, and alternative learning experiences. The simplicity of this justification for outdoor learning can be reductive, in the Boston School Yard Initiative’s guide to outdoor classroom design, they identify the typical image of an outdoor classroom as being a simple AHS, or circle of stones and logs. It is there assertion that “the outdoor classroom is a basic educational resource, like a library or a computer room.” (Boston Schoolyard Initiative, 2013). The utility of outdoor classrooms is better crystalized by Jason Medeiros in his identification of the function of educative landscapes to include inspiration, exploration, reflection, application, and connection. (Mederios, 2010)
Medeiros and the Boston Schoolyard initiative focus heavily on considerations. In Medeiros master’s thesis on educative design there is an apt identification in the way learning experiences happen outdoors through formal teacher led activities, and informal free choice experiences. It is noted that the formal, teacher led activities are better suited to large groups, and therefore require design which established boundaries, focus attention, and allow for management of the group. Conversely, informal learning lends itself to solitary experiences, which require ease of movement, and self-navigation. (Mederios, 2010) In the Outdoor Classroom Design Guide, a variety of functions, elements, and guiding principles are identified in the creation of useful outdoor educational spaces. Perhaps the most general, but potent advice offered is that when designing for learning environments there must be “[…] High educational value, low maintenance, suitability for the site, and sustainability.” This advice in combination with recommendations for incorporating student driven maintenance, consideration for class use alongside student use, and the strategic introduction of elements like fencing, seating, and pathways to create circulation paths and defined spaces for different kinds of learning. (Boston Schoolyard Initiative, 2013)
The remainder of the review is dedicated to identifying resources that will inform the development of technical aspects of the site. One of the more important technical hurdles to overcome is the management of rainwater on the site. In addition to expressed interest by the AHS science department, rainwater harvesting has the benefit of both addressing erosion issues that currently exist on the site, while negating some of the negative impact of drawing from water resources for the garden space. In the Tucson area, Brad Lancaster is a celebrity and champion of water harvesting. Lancaster’s book “Rainwater Harvesting for Drylands and Beyond” is the de facto manual on the topic of rainwater harvesting. Lancaster begins by provided anecdotal support for the use of rainwater, in providing his own home with excellent shade, vegetation, and reduced heating and electricity bills. Lancaster calls for what he has termed “greenfrastructure” to supplement widespread use of grey infrastructure to manage storm water. So called greenfrastructure are earth forms, and plantings which mitigate flooding, and convert that water into a resource in the form of vegetation rather than allowing it to be a wasted resource. Notably, Lancaster’s greenfrastructure is typically low cost, and at most require the investment of tools and labor. Lancaster has divided his manual into three parts, the first volume provides and overview, and context for water harvesting, and sustainable design. The second volume deals with the topic of earthworks, related to the creation of berms and swales. The third volume focuses on the implementation of roof catchment and cisterns. (Lancaster, 2006) The implementation of these techniques will be dependent on what the final analysis of the site will reveal.
The other major technical component of this design will revolve around the selection of an appropriate palette of plant materials for the site. The initial goals of the site were to produce a landscape which was native to near native, and would be able to survive drought tolerant conditions, thus further negating the negative water cost of creating the site, and reducing the impact. For this task there are two excellent resources for selecting plants, and making informed decisions about planting in the Tucson area. Mary Duffield’s “Plants for Dry Climates” provides many resources such as some instructions for planting and care, a plant list, recommended vegetable gardening practices, and a calendar of the blooming season of various colorful flowering plants. In addition to this Duffield provides valuable information which should inform the selection of plants for a site here in Tucson. Duffield defines arid climates as places where evaporation exceeds rainfall, and further explains that heat is not requisite to the definition of a desert climate. In the text, Tucson is defined as a “medium zone climate” which is typified by having mild winters, and a shorter growing season than lower elevation. Additionally, Tucson should experience between 220 and 242 frost free days, with minimum temperatures as low as 18 degrees Fahrenheit, and summer temps typically 5 degrees cooler than at lower elevations. In general Tucson also experiences higher precipitation than lower elevations, and through bimodal rainfall. Duffield states that key considerations for plant selection should account for frost hours, toleration of temperature fluctuation during the day and night cycle, heat exposure, wind exposure, and humidity conditions. Additionally, Duffield discusses microclimates, stating that the boundaries of climates are poorly defined, but generally speaking, there are cold air basins, and thermal belts created by a combination of ground cover, sun exposure, and elevation. Microclimates need special attention as they dictate the success of plant in the space that it is located. Duffield categorizes plants by some of their visual qualities, and groups them according to visual themes like rustic or woodsy. Finally, Duffield promotes the creation of a water budget, which accounts for the amount of rainfall a place receives, with the draw of water needed to maintain plantings. (Mary R. Duffield, 1981). Landscape architect Carol Shuler, is author of “Low Water Use Plants for California and the Southwest”, another book which provides listings for plants appropriate for regions ranging from the Chihuahua Desert, Sonoran Desert, California coast, and all of Baja California. This manual provides slightly more depth with respect to the description of plants, detailing, structural compositions, appearance, height, width, origins, speed of growth, and hardiness. The book shows some of its age ins stating the difficulty of finding native and arid adapted plants in nurseries; while this may be true of chain stores, local nurseries in the Tucson area have made them more available. Shuler promotes the xeriscape gardening, a trademarked term, which has been defined to have multiple meanings, but typically refers to low water use. Shuler contends that Xeriscaping solves problems associated with increasing southwestern populations by alleviating urban heat, attracting wildlife, harvesting rainwater, reducing erosion, and reducing greenwaste. A Particular recommendation that should be taken into account for this project is that plantings should reflect the local wildlife, which means that if local wildlife consists of many birds, or hummingbirds, or bees, that plantings should be used to accommodate them. (Shuler, 1993)