Using laboratory activities enhanced with concept cartoons to support progression in students’ understanding of acid-base concepts

Study context

Science and technology is a compulsory subject between the grade 4 and 8 in the Turkish Educational System and implemented in a spiral manner. The general unit of “The Structure and Properties of Matter” is included in grade 8 curricula. This unit comprises five sub-units and one of them is acids and bases. In this unit, students are expected to gain eleven learning goals and these are listed in below (URL, 2012).

Learning goals related to acids and bases in the curriculum

Students;

1. Know the acids and bases with their properties by touching, tasting and seeing.

2. Associate the acids to H⁺ ion, and the bases to OH ^– ion.

3. Know that species such as SO₂, Na₂CO₃ and NH₃ react with water to produce H⁺ ion or OH ^– ion, and write suitable equations for these reactions.

4. Understand that pH is an indicator of acidity and/or basicity of a solution and associate the pH scale to acidity and basicity.

5. Know the acids and bases commonly used in foods and cleaning materials.

6. Know that CO₂ found in most carbonated beverages produces H⁺ ion in water, namely it pretends an acid.

7. Know the pH values of some acids and bases commonly used in daily life.

8. Know the market names of some common acids and bases as well systematic names.

9. Show the interaction between acids and bases, experimentally; call this interaction as “neutralization reaction”; and define the products of such reactions.

10. Explain why they must be careful while using acid and base solutions.

11. Explain the negative effects of acids and bases on matter used in daily life.

As seen from the table, students in both groups took the same content during the implementations. In other words, the same content was taught to students in both groups with different instructional techniques in eight 40-minute lessons.

Research Design

A quasi-experimental method was used in the study because the participants of the study were already distributed to classrooms by the school management. Because school authorities did not allow the researchers to constitute new classrooms for experimental purposes, they randomly assigned the present groups as experimental and comparison groups. Among the different designs of this method, “pretest – posttest non-equivalent groups design” (Robson, 1998) was chosen for this inquiry and one comparison group (CG) and one experimental group (EG) were used to collect data. Each group was given both a pretest and a posttest to collect data.

The Sample

The subjects for the study consisted of 36 eighth grade students (19 boys, 17 girls) from two intact classes of a primary school in a city of Turkey. One class (N = 19; 11 boys and 8 girls) was assigned as the experimental group (EG) and the other (N = 17; 8 boys and 9 girls) was chosen as the comparison group (CG).

Instruments

Acid-Base Achievement Test (ABAT) and students’ interview were used to collect data in the study.

Acid-Base Achievement Test (ABAT)

The ABAT contains 25 multiple-choice questions. Each of them includes four choices, one of these is scientifically acceptable answer and rests of them are the plausible distracters. While 14 of the questions were taken from different test books used in the schools and literature with minor revisions (Artdej, Ratanaroutai & Thongpanchang, 2009), the researchers prepared 11 of them. The reliability of the test was estimated to be 0.83 using the Kuder-Richardson 20 formula, which was considered acceptable for an instrument of this type. Table 1 summarizes the characteristics of the ABAT.

Table 1. Characteristics of the acid-base achievement test (ABAT)

Areas evaluated	:	Description of acids and bases: items 1, 2 and 6 General properties of acids and bases: items 8, 22 and 25 Common properties of acids and bases: items 4, 13 and 19. Properties of acids and bases used in daily life: items 3, 10 and 23 Interacts of acids and bases used in daily life: items 5, 9, 11 and 24 Acid and base reaction: 7, 16 and 21 The meaning of pH values of acids and bases in daily life: 12, 15 and 18 Relationship between the [H⁺], the [OH^-], and pH; 14, 17 and 20
Number of items	:	25
Response format	:	Multiple-choice
Time to complete test	:	30 to 40 minutes
Discrimination indices	:	Mean range (items) 0.46 0.30-0.39 (8) 0.40-0.49 (10) 0.50-0.59 (5) 0.60-0.69 (1) 0.70-0.79 (1)
Difficulty indices	:	Mean range 0.55 0.20-0.29 (3) 0.30-0.39 (1) 0.40-0.49 (5) 0.50-0.59 (4) 0.60-0.69 (10) 0.70-0.79 (1) 0.80-0.89 (1)
Kuder-Richardson	:	0.83

The difficulty indices ranged from 0.20 to 0.89, providing a wide range of difficulty items. The discrimination indices ranged from 0.30 to 0.79. A value of 0.30 was established as a minimum, and those greater than 0.30 were considered acceptable without the need for further revision of the test items (Peterson, Treagust & Garnett, 1989). The content validity of the test was established by a commission consisting of three chemistry educators from the university, two-experienced chemistry teachers and six science and technology teachers. The ABAT was used in the pretest/posttest format for the study to determine students’ understanding. The final version of the ABAT is given in Appendix 1.

Students’ Interview

As mentioned above, the research design included two groups, one (EG) included the laboratory activities enhanced with concepts cartoons and the other (CG) was taught with laboratory activities without concept cartoons. Eight students from the EG and eight students from the CG were interviewed individually for 25-30 minutes before the implementation (pre-interview). A semi-structured approach was used in the interviews, eleven questions were asked to all students and all of which were audio taped and transcribed verbatim. Data from pre-interview were used to determine students’ alternative conceptions, to design laboratory activities, to construct the phrases found in cartoons, and to develop the items of the ABAT. Therefore, findings of the semi-structured interviews were not given in results and discussion section.

Preparing the Concept Cartoon Enhanced Worksheets

The intervention applied in the EG includes five laboratory activities enhanced with concept cartoons. These activities were prepared in worksheet format and covered five major conceptual areas. These are; let’s diagnose acidic and basic properties of matters (Worksheet A), effect of acids and bases on different matters (Worksheet B), electrical conductivity of acids and bases (Worksheet C), reactions between acids and bases (neutralization) (Worksheet D), and determination of the pH values using pH paper (Worksheet E). The researchers consistent with a constructivist-based manner in a three-step format prepared worksheets. These steps are enter, activity and explanation, and evaluation. In the enter step, concept cartoons were used to attract students’ attention and to determine their pre- and/or alternative conceptions related to acids and bases. In the concept cartoons, cartoon characters phrased their alternative viewpoints about the acids and bases involved in the situation in the balloons. While one of these views was correct, the others were not scientifically acceptable. The aim of this stage is to help students realizing their alternative or/and inconsistent views. In the activity and explanation step, students performed the activities and recorded their data on tables in the worksheets. After that, the results were discussed with whole class and teacher made some explanations. In the evaluation step, students asked to respond the questions, which were related to concepts, activities and daily life applications. All of the worksheets used in the study aimed to activate students’ previous knowledge, to reveal alternative conceptions and to remedy them to scientific ones. For this aim, each of the worksheets was responsible in altering one or more alternative conceptions. One of the worksheets used in the study is given in Appendix 2 (Worksheet A).

Implementation Process

In the study, the whole content of the acids and bases unit in grade 8 was taught applying different teaching approaches for the EG and CG in the same number of lessons. The groups were taught by two different teachers. The control group’s teacher was male and had 10 years of science teaching while the experimental group’s teacher who was female and had 8 years of science teaching experience. In both groups, teaching of the acids-bases unit took eight 40-minute lessons. The ABAT was applied to both groups before and after the implementation, as pretest and posttest. If someone examine the educational attainments related to acids and bases sub-unit (see Table 1), (s)he can see that same content were taught to students in both groups. For example, the teachers taught the same concepts, gave the same definitions, made the same experiments in both groups. The main difference between the groups was based on the concept cartoons. Teacher in the EG used the concept cartoons to activate students’ pre-conceptions and to dissatisfy them with some beliefs. On the other hand, concept cartoons were not used in the CG. In addition, while the EG’s teacher took into consider the students’ alternative conceptions determined with pre-interviews and from the literature related to acids and bases, the CG’s teacher did not make this.

Teaching Approach Used for the Comparison Group

In the CG, teacher was asked to teach the unit as he had done in the past. Instruction was made in laboratory environment. During the lessons, teacher tried to make a student-centered instruction based on the laboratory activities, discussions and oral explanations. Textbook was used as principal source and it included different activities related to acids and bases. In the process, students made some activities; teacher tried to activate students by questions and class discussion, explained the important concepts related to acids and bases such as acid and base definitions and then wrote commonly known examples on the board. In this process, students made some laboratory activities found in the textbook such as diagnosing acids and bases by using litmus paper, determining the effects of acids and bases on matters etc. themselves as group. Besides, students were asked to taste some acids and bases known from daily life such as lemon juice, vinegar, soapsuds, and toothpaste. During these tasting, students were distributed worksheets and asked them to write the taste of matters. While the students were studying these activities, the teacher walked around the classroom helping them as needed. During the activities, the students had the opportunity to ask questions. Teacher made some explanations related to properties of acidic and basic matters, diagnosing acids and bases by using litmus paper, neutralization reactions, common acids and bases used in daily life, and relation between pH and acidity. Besides, he responded the students’ questions. In addition, Although Arrhenius definition was considered during the definitions, teacher also emphasized that containing H or OH in the formula is not an indicator for acidity or basicity of some species. For example, a species not having H in its formula can pretend an acid in its aqueous solution; and another species not having OH in its formula can pretend a base in its aqueous solution. CO2 and NH3 are the most suitable examples for these, respectively.

In summary, students in the CG took part in the learning process actively and made some activities in this process. However, they did not use the concept cartoons and did not discuss the pre- or alternative conceptions before the instruction. Moreover, teacher did not mention students’ possible alternative conceptions during her instruction.

Teaching Approach Used for the Experimental Group

Before the implementation process, teacher and authors discussed the purposes of the laboratory activities, the role of concept cartoons and teaching approach for the EG. Implementations were done in laboratory environment. Each of the worksheets were distributed to students and asked them to examine the enter section, individually. After that, students were expected to write down their observations in the blank areas below the concept cartoons. After they finished writing, the students were told about common alternative conceptions that were determined from pre interviews and literature. The ideas were discussed with the students. This discussion aimed to develop potentially cognitive conflict in the students when they subsequently conducted the laboratory activities. The main aim here was to help students to see that they needed to consider competing explanations for their observations. After the discussion was finished and students’ explanations related to concept cartoons found in the enter section of the worksheets were taken in written, teacher grouped the students for activities in the second step. These groups were designed to be similar, and heterogeneous in terms of students’ performance as based on the pre-interviews. Students carried out the activities in groups of four to six students, and teacher walked around the tables and asked some questions related to activities to help and canalize them. After the students had finished the activities, the results were presented and discussed with the whole class and teacher emphasized important points of the topic in order to make students’ minds clearer. During discussions, alternative conceptions held by the students before the activities were re-evaluated and this gave the students an opportunity to compare their previous and new knowledge. Such an approach aimed to correct students’ alternative conceptions and to present scientific information behind the activities. In last step, conceptual questions related to activities and daily life situations for acids and bases were asked to students to elaborate and transfer their knowledge.

Data Analysis

In the analysis of the ABAT, firstly, the total score of each student in both groups were calculated. For this aim, each correct answer for the 25 multiple-choice items was given 4 point, and if a student responded to all questions correctly, a maximum of 100 points was possible. The pretest scores of the groups were compared by using independent t-test to determine whether a statistically significant mean difference existed between two groups. Because there was no significant difference between pretest results, the posttest scores were also compared by using independent t-test to see the effects of intervention on students’ understanding of acids and bases.