Results

Student performance was assessed using pre- and post-tests. The methodology included administering a pre-test, conducting a field trip, performing lab analysis, interpreting measurements using a guided inquiry and finally taking a post-test. Pre-tests and post-tests were administered to assess the knowledge gained on chemical equilibrium by the pre-education students enrolled in the chemical education course at Wright State University. The guided inquiry (see Teacher’s guide) uses carbonate equilibrium since it controls the chemistry of natural water. The Mad River drains from a watershed that has a calcite bed underneath. Relevant equations describing carbonate equilibrium and calcite dissolution were included. The reactions included dissolution of carbon dioxide and oxygen gases from air, aqueous speciation, and calcite precipitation and dissolution. The guided inquiry then allows students to tabulate data gathered from field and laboratory. The following table shows typical data obtained from a field trip to Mad River Ohio by the Huffman Dam.

Location / Parameter	Flow	Temp.(^0C)	pH	Dissolved Oxygen (mg/L)	Calcium Hardness (mg/L)	Total Carbonate (mg/L)	Phosphate mg/L
Upstream	Slow	22.3	8.7	9.4	180	0.0024	4
Downstream	Fast	23.1	8.4	9.2	140	0.0020	2

Then the guided inquiry allowed teachers to predict dissolved oxygen (DO) both upstream and downstream using Henry’s law. The students verified the calculated DO with measured DO on the stream and using a nomograph. They compared the orthophosphate levels measured on the stream with estimated values assuming calcium phosphate as the controlling solid phase. They also estimated pH upstream using carbonate equilibrium and compared with the observed pH on the stream. The estimated value was in close agreement with the measured value.

Questions in the guided inquiry were based on two phase equilibrium between water and air; determination of pH upstream and downstream of the dam by solving aqueous phase chemical equilibrium, and prediction of pH of water near the outcrop using equilibrium between aqueous phase carbonate species and solid phase mineral calcium carbonate. There was no lecture in the guided inquiry. Student learning had taken place through experiences in the field trip, basic information provided on water quality and geology, lab experiences, and guided inquiry.

The authors used the traditional mode of lecture and reading from the prescribed textbook prior to adopting this guided inquiry. The traditional method was employed to the same class and was preceded by a pre-test and followed by a post-test. A handout on chemical equilibrium comprising of the chapter from the textbook and supplementary notes was distributed to the students. The instructor used the handout to teach concepts. The students enrolled into this education class for middle school childhood teachers who did not have any prior background on chemical equilibrium and their background in basic chemistry was found to be weak. This reflected as zero scores on their pre-test. Most students returned their pre-tests indicating that they were unaware of the concepts how reactions related to real world problem solving based on chemical equilibrium incorporating soil and water quality. Since the handout only focused on describing the general concepts and theory with few examples to real world analysis, students could not apply themselves to solve the problems on the post-test. A combination of lack of problem solving ability and deeper understanding of the concepts among students when taught using the traditional method may have contributed to their similar performance on the post-test. The time allotted for teaching this chapter was one week in the traditional setting which made any enrichment using laboratory exercises difficult. The lack of any comprehension using the traditional method to a class with weak/no prior background in chemistry encouraged instructors to adopt the above discussed guided inquiry approach integrating concepts across chemistry, geology and water resources. The field trip provided association of abstract concepts to concrete examples such as water, rocks, and minerals.

With the traditional mode of lecture, students had no prior understanding of the concepts on chemical equilibrium (0% on pre-test) and also there was no gain achieved from the traditional lecture (0% on post-test). However, in the inquiry mode of teaching an average pre-test score of 0% and an average post-test score of 60.0% with a normalized gain of 0.60 was attained. The class standard deviation was found to be 18%. Normalized gain was calculated using the formula: (post-test - pre-test) / (100-pre-test). The pre-test/post-test was included in the Teacher’s guide. These results were obtained for a class of 35 students. As discussed before both the traditional mode and inquiry mode of teaching were carried out each for one week period. The resulting 60.0% increase in percentage points from the pre- and post-tests results of 35 students are consistent with the noted trend of improved student understanding with increased interactive science courses. In addition to the pre- and post-tests, the pre-education students in the OHEN project were given a questionnaire about their views on science instruction and teacher preparation. An analysis of this survey suggests that teaching concepts in chemistry using a combination of field trips and laboratory work reinforces an undergraduate science teacher’s opinion about science instruction using inquiry (9-10). The pre-service teachers who are education majors expressed greater comfort in learning these concepts using a real-world application such as prediction of water quality in a river. Overall, the pre-education students’ comments regarding this inquiry-based chemical equilibrium packet have been positive and enjoyable compared to the traditional lecture on chemical equilibrium.