Assessing Middle and High School Students\u27 Conceptual Understanding about Photosynthesis

My study investigated two major research questions regarding photosynthesis education. 1) To what extent do middle and high school students understand the following five major concepts about photosynthesis and cellular respiration before and after instruction: (a) chlorophyll is necessary for photosynthesis, (b) light is the energy source for photosynthesis, (c) carbon dioxide from the atmosphere is the carbon source for plants, (d) plants undergo cellular respiration, and (e) cellular respiration occurs within all cells. 2) Does there appear to be a relationship between how well teachers are able to predict their students\u27 responses as a class on the post-survey and the class\u27s normalized gain? To test these research questions, pre- and post-surveys were administered to five middle school and four high school classes in Maine about photosynthesis (n = 335 students; n = 9 teachers). Teachers answered a methods survey regarding the materials they planned to use, what concepts they were planning to cover, and completed a pedagogical content knowledge survey that asked teachers to predict their students\u27 responses to the post-survey. All surveys were administered between September 2008 and April 2009. The main finding (Finding 1) from the results of the student surveys was that middle and high school students in my study lacked the conceptual knowledge about photosynthesis that is required by national and state science standards. Finding 1 has two implications: 1) middle and high school students in my study did not learn the concepts that they are expected to understand as outlined in the science standards, and 2) middle school students are not entering high school with an accurate conceptual understanding about photosynthesis. The main finding (Finding 2) from the results of the teacher surveys is that classes with gains in understanding after instruction were more likely to be taught by teachers who had higher PCK scores (matched predictions). This finding was especially evident in the questions that assessed concepts in which students were shown to have deep-rooted misconceptions. Based on these two findings, I propose suggestions for future research and recommendations for the classroom, including a revised photosynthesis concept survey