Reading passage: In the past century, the steady growth of the human population and the corresponding increase in agriculture and pesticide use have caused much harm to wildlife in the United States—birds in particular. Unfortunately for birds, these trends are likely to continue, with the result that the number of birds in the United States will necessarily decline . First, as human populations and settlements continue to expand, birds’ natural habitats will continue to disappear. Forests, wetlands, and grasslands will give way to ever more homes, malls, and offices. As the traditional areas suitable for birds keep decreasing, so will the size of the bird populations that depend on those vanishing habitats. Second, agricultural activities must increase to keep pace with the growing human population. The growth of agriculture will also result in the further destruction of bird habitats as more and more wilderness areas are converted to agricultural use. As a result, bird populations in rural areas will continue to decline. Third, as human settlements expand and agriculture increases, the use of chemical pesticides will also increase. Pesticides are poisons designed to kill agricultural and home garden pests, such as insects, but inevitably, pesti- cides get into the water and into the food chain for birds where they can harm birds. Birds that eat the poisoned insects or drink contaminated water can die as a result, and even if pesticides do not kill birds outright, they can prevent them from reproducing successfully. So pesticides have significantly contributed to declines in bird pop- ulation, and because there will continue to be a need to control agricultural pests in the future, this decline will
continue. Lecture:
Listen to the lecture based on Bird Populations
Exercise 3 Instructions This is an opportunity to get more practice with an Integrated item. Follow the same instructions that are provided for Exercise 2 . Reading passage: Carved stone balls are a curious type of artifact found at a number of locations in Scotland. They date from the late Neolithic period, around 4,000 years ago. They are round in shape; they were carved from several types of stone; most are about 70 mm in diameter; and many are ornamented to some degree. Archaeologists do not agree about their purpose and meaning, but there are several theories . One theory is that the carved stone balls were weapons used in hunting or fighting. Some of the stone balls have been found with holes in them, and many have grooves on the surface. It is possible that a cord was strung through the holes or laid in the grooves around the ball. Holding the stone ball at the end of the cord would have allowed a person to swing it around or throw it. A second theory is that the carved stone balls were used as part of a primitive system of weights and measures . The fact that they are so nearly uniform in size—at 70 mm in diameter—suggests that the balls were interchangeable and represented some standard unit of measure. They could have been used as standard weights to measure quantities of grain or other food, or anything that needed to be measured by weight on a balance or scale for the purpose of trade . A third theory is that the carved stone balls served a social purpose as opposed to a practical or utilitarian one. This view is supported by the fact that many stone balls have elaborate designs. The elaborate carving suggests that the stones may have marked the important social status of their owners.
Listen to the lecture based on Carved Stone Balls
Reflection Think about the experience of working with materials for two different Integrated tasks, in Exercises 2 and 3. Do you feel more confident now about responding to Integrated tasks? Why or why not?
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