8.50 Teaching Biology In developing a standard for assessing the teaching of precollege sciences in the United States, an experiment was conducted to evaluate a teacher-developed curriculum, "Biology: A Community Context" (BACC) that was standards- based, activity-oriented, and inquiry-centred. This approach was compared to the historical presentation through lecture, vocabulary, and memorized facts. Students were tested on biology concepts that featured biological knowledge and process skills in the tradi- tional sense. The perhaps not-so-startling results from a test on biology concepts, published in The American Biology Teacher, are shown in the following table. 12

a. Find a 95% confidence interval for the mean score for the posttest for all BACC classes.

b. Find a 95% confidence interval for the mean score for the posttest for all traditional classes.

c. Find a 95% confidence interval for the difference in mean scores for the posttest BACC classes and the posttest traditional classes.

d. Does the confidence interval in part c provide evidence that there is a real difference in the posttest BACC and traditional class scores? Explain.

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Standard Meant Sample Size Deviation Pretest: All BACC classes 13.38 372 5.59 Pretest: All traditional 14.06 368 5.45 Posttest: All BACC classes 18.5 365 8.03 Posttest: All traditional 16.5 298 6.96