Activity One – What is an Acre? Time: approximately 15 minutes
In Canada and the U.S., the preferred unit of measure for an area of land is the acre. In the rest of the world, where the Interna- tional System of Units is predominant, the hectare (ha) would be the unit of choice for this activity. For the sake of this activity we will use acre, but know that it can easily be switched out. (1 ha = 2.47 ac or 1 ac = 0.404 ha) This activity is best done in a large outdoor area but could be done in a gymnasium if scaled down.
Materials: four land markers (such as pylons), and a long tape measure (100 metre) or a trundle wheel.
Procedure: 1. Take your class to a suitably sized space, preferably the school yard. Ask students, “What is an acre?” Most will have some idea that it is a measure of area.
2. Ask students, “How big is an acre?” This will pose a greater problem for students. 3. Ask for three volunteers. Give one of the pylons to each of the student volunteers and keep one for the teacher. The teacher then places the first pylon on the ground/floor and indicates that this is starting point in one corner of an acre. Then have the volunteers walk or run to where they think the other corners should be. Tell them that for this exercise, their acre should be square. Most classes will usually estimate the size of an acre of land to be a little smaller than it actu- ally is. It is actually 208 feet by 208 feet. For me this works out to approximately 63 paces, a rough measurement tool I use if I do not have a long tape measure with me.
4. Once the students have placed their pylons, ask the others if they think this is close to representing an acre? Then you or one of the students can use the trundle wheel to measure 208 feet (or 63 paces) from the first pylon. Move the other three pylons to represent the desired area of an acre.
5. Ask students to guess what the size of an average farm is in Canada? (778 acres) NOTE: The average farm is very difficult to describe as some specialty crop farms may such as strawberries or vineyards may only be a few acres while other cereal crop farms may be thousands of acres) In the U.S.? (434 acres), and in India (1.33 hectares). In much of the world small hold farmers may farm only a few acres.
Now imagine and average farm. That would be 778 of these acres in Canada or 434 of these acres in the USA. Now imagine a
large farm – thousands of acres! That seems like such a huge amount of space that is taken up for agriculture but in fact it is only a small fraction of the earth’s surface. The food for a population estimated to be growing to 9 billion by the year 2050 must be fed with the food from this land. The challenge is to produce enough food in a sustainable manner so the environment, society and economy are not impacted in a negative way.
Activity Two – The Bushel Basket Time: 30 minutes
In Canada and the U.S., the preferred unit to measure crop yield is the bushel. The story of the bushel and its historical change is a lesson unto itself, but for the purpose of this activity we will revert to more of a traditional definition of a bushel as a unit of volume. In most of the world, the kilogram or metric tonne would be the unit of choice for measuring yield, and as such the activity could easily be converted as need be.
Materials: Bushel basket(s) – one per crop to be discussed; Cardboard; Garbage Bag(s) or cloth; Samples of crops to be discussed or pic- tures of seeds (e.g wheat, corn, soybeans); Containers (e.g. 1L and 2L soda/pop bottles; Nitrogen fertilizer sample; Phosphorus fertilizer sample; Potassium fertilizer sample.
Advance Preparation: Create a false top for each bushel basket using cardboard and cover with a garbage bag or some cloth. Then place the crop sample on top of the garbage bag so that the bushel basket will look full. The garbage bag aids in the clean- ing up of the seeds and putting them back into the storage containers. If actual seeds are not available, pictures of seeds could be used instead. The appropriate size of samples of nitrogen, phosphorus and potassium nutrients (see Table 1) are placed in containers (clear 1L and 2L soda bottles work well). It works well to split each nutrient into two parts – one part represents the nutrient removed with the seed and the second part represents the nutrient left in the straw and residue that is left behind after harvesting.
GREEN TEACHER 113 Page 41
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