Feasibility of Modifying Existing Chemistry Demonstrations by Using Substitute Materials

This study aimed to reiterate the use of Chemistry demonstrations as effective teaching tools to students while addressing some of its drawbacks, which discourages teachers from doing them such as cost and safety. Four chosen existing Chemistry demonstrations (Blue Bottle Experiment, Copper Sulfate Experiment, Blown Away, Dancing Flames) were modified by using substitute reagents, which are more accessible, relatively safer, and at lower cost. These demonstrations were chosen based on how easily the substitute reagents will be obtained. Afterwards, with the permission of a private junior high school, they were presented to a group of Grade 9 students of their choosing. The students were asked to evaluate each demonstration using a Likert scale-based questionnaire. This questionnaire rates each demonstration in terms of aesthetics, the materials overall judgment regarding the use of demonstrations as teaching tools. By converting their evaluation to quantitative values, the demonstrations scored high in all major categories. With this, it is highly recommended to explore other Chemistry demonstrations for possible modifications, which can be integrated in lecture classes. Chemistry demonstrations; Introductory Chemistry; Likert scale-based questionnaire


INTRODUCTION
In the field of Science, Chemistry has always been one of the more exciting sciences to learn about because different products and phenomena that we see in real life can be explained. It is also where the other branches of Science such as Biology and Physics come together, which makes it all the more interesting.
But at the same time, this makes it one of the more complicated sciences both to learn and to teach. As a student, one of the most challenging parts of learning Chemistry is being able to understand the concepts from the macro level. The fact that Chemistry primarily deals with particles that cannot be seen by the naked eye and that there are a lot of things going on makes it even more difficult. This is why Chemistry courses, or Science in general, should be supplemented by laboratory classes (Hered, 1950). But due to lack of facilities and equipment especially in public schools in developing countries, most students are not able to experience that. This is more difficult to teachers too because with the lack of lab classes, they resort to teaching by the book and rely on visual aids such as pictures and videos. What is worse is that some teachers cannot afford visual aids due to the lack of facilities and financial problems. This might decrease the field in the future.
One of the alternatives to laboratory classes that can be done is by doing demonstrations wherein instead of just watching an experiment during a lecture, the teacher executes the experiment while the rest of the class observes. One of the skills, which they can still develop through this even without the typical laboratory experiments is problem-solving skills (Meyer et al., 2003). They will be encouraged to ask questions about what happened and even draw inferences of what they think happened during the demonstration. Their observational skills will also be honed just like in a learn to be conscious of the different changes happening in the demonstration. This will also result in a constant student-teacher interaction as compared with a typical lecture wherein the professor g experience more effective. A method of teaching that encourages team learning and student-led discussions (such as chemistry demonstrations), as compared to a normal lecture teaching, favors better performance of the students (Carpenter, 2006) since it encourages more participation in class boosting their self-confidence.
Despite this, using this method is still not widely used due to various reasons. One reason is because it is time-consuming (Walton, 2002) considering that the bulk of their time is allotted for preparation of their lesson plans (Meyer et al., 2003). Time is not only needed in preparing the demonstration, but it is also needed in trying-out the demonstration, preparing the necessary points that the educator wants to emphasize, and looking out for safety precautions that needs to be observed. Another hindrance is the misconception that demonstrations need expensive kits or materials (Meyer et al., 2003).
This study aims to modify pre-existing Chemistry demonstrations that can address the reasons stated above by using substitute reagents, which are better than the original in terms of accessibility, safety, and cost. Necessary revisions to the procedures were done to replicate the result of each original demonstration. Afterwards, as a supplement to the study, these demonstrations were presented to a group of high school students from a private junior high school. Each demonstration was evaluated using a Likert scale-based questionnaire which is based on the given criteria.
The use of demonstrations in lectures has been supported by a lot of studies worldwide over the Paul Walton, a chemistry faculty member at the University of York involved getting responses from freshmen undergraduate students who attended an Acids and Bases lecture with integrated demonstrations. They were given a set of statements and were asked if they agree to each or not. The results showed that 87% (either totally or partially) agreed that demonstrations helped them Volume 31, Number 2, July 2020 KIMIKA understand the theories behind the lesson. Moreover, 95% (either totally or partially) agreed that the demonstrations kept their interest during the lecture (Walton, 2002).
Another study was conducted by Ophardt, Applebee, and Losey in 2005, which involved students from nonscience major courses in Elmhurst College. In their laboratory course, they performed various chemistry demonstrations in class and eventually in front of students from a local elementary school. The students were then asked to give their thoughts on the course in terms of their learning objectives and comparing it with the traditional laboratory setting. Their questionnaires have statements, which they rate in a 1-5 range, with 5 being the highest. The results showed high average scores when talking about their learning objectives. These include learning basic chemistry concepts (score: 4.67) and strengthening the interest in science (score: 4.28). Comparing with traditional science labs, students preferred their demonstration-focused lab. Areas of question include interest in activities performed on a given day (score: 4.42) and freedom to learn at their own pace (score: 4.00) (Ophardt, et.al., 2005). The latter result proves that chemistry dem al., 2003).

METHODS
Existing chemistry demonstrations were modified by replacing the reagents with more accessible materials with lower cost. The chemistry demonstrations were chosen based on the availability, accessibility, and affordability of possible substitutes, particularly in the Philippines. Since all the demonstrations are adequately documented in various sources, these became the visual models of what the demonstrations (experiments) should look like. They became the basis in possible changes in formulation of the materials, comparing the original and the substitute.
As a supplement to the study, the demonstrations were presented to a group of 24 junior high school students in a private junior high school. The sample size and respondents were chosen by the school itself based on their schedule as well as the relevance of the prepared demonstrations to their current curriculum. Afterwards, they were given a Likert scale-based questionnaire where they were asked to evaluate the presented demonstration (See Supporting Information A). This work was granted a Validation of Exemption from Review by the Ateneo de Manila University Research Ethics Office (UREO).
The 10-item questionnaire is based on five major categories that was deemed important in evaluating a Chemistry demonstration. Items # 1 and 6 fall under the Attention Getting category, . The second category is Technical Procedure (items # 2 and 4), which assesses the demonstration materials and procedure. This also includes accessibility and difficulty. The third category is Lecture Value (items # 3, 5 and 7), which deals with the effectiveness of the demonstrations to the respective Chemistry topics that they were connected to. Fourth category is Safety (item # 8), which rates the overall safety of each demonstration, i.e., if it is possible to do each demonstration outside the laboratory and if it is without any extreme danger to the students and teacher. The last category is Overall Judgment (item # 9 and 10), which rates the overall reaction of the students to the demonstrations. It rates how helpful the demonstrations can be if they are applied as teaching tools during lectures.
KIMIKA 31, Number 2, July 2020 The following are the modified demonstrations: 1. Blue Bottle Experiment this involves the reduction-oxidation reaction of dextrose and methylene blue in a basic solution (See Supporting Information B); 2. Copper Sulfate Experiment this is a reversible reaction which involves the dehydration of copper (II) sulfate (See Supporting Information C); 3. Blown Away this is a precipitation reaction between calcium hydroxide and carbon dioxide (See Supporting Information D); and 4. Dancing Flames this is a single displacement reaction between copper (II) sulfate and aluminum in acid (See Supporting Information E).

RESULTS AND DISCUSSION
The main reagents of each demonstration as written and published in online journals and respected websites are shown in Table 1 indicating as well the list of the substitute materials and their cost of purchase at the time of the study. Using these substitutes, the results of the original Chemistry demonstrations were replicated with some modifications in the procedure.
The Likert scale responses were translated into a numerical value using the criteria suggested by Joshi et al. (2015) where the Likert scale can be treated as an interval scale, which is usually a five or sevenwhich were then fit to a score range. Each were given a corresponding interpretation to obtain a qualitative result. Afterwards, these mean scores were combined to report all demonstrations as one in each of the categories. Table 2 showed that all the presented Chemistry demonstrations afforded positive results in all categories, with the mean scores equivalent to the Very Good to Excellent range. Supported by the low standard deviations measured from all categories, it can be inferred that the students enjoyed the demonstrations and that they saw the demonstrations being beneficial in understanding the Chemistry topics.
Choose the demonstrations whose materials can be modified.
Test the feasibility of using the substitutes.  score of 6.25. The students thus agree that the use of Chemistry demonstrations in general draws interest in the lecture (Walton, 2002). On the other hand, Technical Procedures (score: 6.14) and Safety (score: 6.05) having high mean scores can address the hesitations the educators have in doing demonstrations as highlighted in this study. Addressing the safety and accessibility concerns by using cheaper and safer substitute reagents suggests strong potential of these experiments for easy integration to lesson plans and curricula. The feasibility of the modified experiments using substitute materials have been successfully demonstrated to achieve its purpose in reinforcing a topic in Chemistry.

CONCLUSION
The study was successful in modifying existing Chemistry demonstrations by using substitutes that are more accessible, relatively safer, and at a lower cost. With some modifications in the procedure, the end result of each original demonstration was replicated. The Chemistry demonstrations were evaluated with positive results in all categories. This shows that the modified selected demonstrations can be used with confidence. The positive feedback also addresses, and possibly removes, some underlying reservations such as cost and safety in allowing students to do the experiments. In general, this study can help further push and encourage the use and integration of Chemistry demonstrations in school curricula today.

SUPPORTING INFORMATION A: Likert Scale
As part of the reported results of the current study, the principal investigator would like you to answer this questionnaire about the chemistry demonstration that you have watched. Please answer as objectively as you can. Rest assured that only the principal investigator will see your individual responses and you will not be asked for any personal information.
Please check the box which describes your response to the following observations. experiment presented, not the whole session. Explanation Different reactions are taking place during the color change as seen below but the more important reaction is the reduction and oxidation of methylene blue. When the bottle turns blue to colorless, methylene blue is reduced by the dextrose powder through its enediolate anion in alkaline solution to produce methylene white (MBH) which is another name for reduced methylene blue. On the other hand, when the bottle turns colorless to blue, methylene white (MBH) is oxidized by oxygen inside the bottle (See 4-5 in the figure) (Anderson et al., 2012).