Fostering Active Chemistry Learning in Thailand: Toward a Learner-Centered Student Experiences

Abstract

Coll, Dahsah, Chairam, and Jansoon state in Chapter 16, that Thailand like many countries worldwide has engaged in major reforms to the science curriculum. A key focus of these reforms has been a shift toward a learner-centered science curriculum. In this chapter, authors report on a number of studies to show how a learner-centered science curriculum in Thailand places major importance on shifting the mindset of Thai students from a rather less active learning role in a strongly teacher-dominated classroom to a role in which they are active learners of chemistry.

Appendices

Appendix A

Stoichiometry Learning Unit: 2

Subject: Chemistry	Level: Grade 10
Topic: Average atomic mass	Time: 1 period (50 min)

Learning Outcome

• 1. Students should be able to define the meaning of an average atomic mass;

• 2. Students should be able to do the experiment and calculate average mass of objects

• 3. Students should be able to calculate atomic mass of an element

• 4. Students should be able to describe how scientists determine average atomic mass using mass spectrometer.

Science Concept

The average atomic mass of an element is the average atomic mass for the naturally occurring element, expressed in atomic mass units. The scientist uses mass spectrometer to determine the isotope of element and average atomic mass.

Learning Activities

Express and Share Ideas

• 1. Explore students idea about number of basic particles in atoms and isotope (Worksheet I)

• 2. Demonstration using red and green balls to explore students’ prior knowledge about atomic number, mass number, and isotope. Discuss the responses in class. (Isotope demonstration)

• 3. Predict how scientist determines the atomic mass of the element that has isotope. Discuss in group and in class

Challenge Ideas

• 4. Do analogy experiment about average mass of beans (Worksheet II: Average Mass Experiment)

Accommodate Ideas

• 5. Discuss the analogy experiment and link to the concept of average atomic mass

Apply Ideas

• 6. Calculate an average atomic mass of an elements (Worksheet III)

• 7. Search for information about mass spectrometer and how scientists use it to determine atomic mass. Present in next class.

Instructional Materials

Worksheets and Demonstration equipment

Assessments

• 1. Students’ response; discussion, presentation both in group and in class

• 2. Do experiment

• 3. Group activity

• 4. Worksheet

• 5. Searching and Report

• 6. Students’ Journal.

Worksheet I

Atomic number, Mass Number, and Isotope

• 1. Complete the following table

  Symbol	Number of Proton(s)	Number of Neutron(s)	Number of electron(s)	Atomic Number	Mass Number
  ${}_{1}^{1} {\text{H}}$
  ${}_{1}^{2} {\text{H}}$
  ${}_{1}^{3} {\text{H}}$
  ${}_{6}^{12} {\text{C}}$
  ${}_{6}^{13} {\text{C}}$
  ${}_{6}^{14} {\text{C}}$
  ${}_{7}^{14} {\text{N}}$
  ${}_{7}^{15} {\text{N}}$

• 2. Are there any Isotope shown in the table from item 1? Explain

• 3. What is atomic number?

• 4. What is mass number?

• 5. What is isotope?

• 6. If an element that has isotope, how do we define the atomic mass of that element?

Worksheet II

Average Mass Experiment

Instruction: Group of three students find out the average mass of beans

Pre Questions:

• 1. What are average weight of boys and girls in our class?

• 2. What is average weight of the student in a class from the information in item 1?

• 3. How to find out the average mass of seed of bean in a beaker?

• 4. If we have three types of bean, and know average mass of each bean, how do we determine the average mass of bean?

Materials:

Three beakers, black beans, soy beans, green beans, digital balance

Procedures:

• Weight mass of each bean in the given amount

• Count the number of each bean in the given amount (about 40–100 seeds)

• Calculate average mass of each seed

• Calculate percentage of each bean compare to all beans

  e.g ${\text{percent of green bean }} = \frac{\text{number of green bean}}{\text{number of all beans}} \times 100$

• Calculate average mass of one seed of bean

$\begin{array}{ll} {\text{Average mass of beans}} \,=\, \hfill \\ \frac{{\left( {{\text{mass of green bean }} \times \, \% {\text{ of green bean}}} \right) + \left( {{\text{mass of soy bean }} \times \, \% {\text{ of soy bean}}} \right) + \left( {{\text{mass of black bean }} \times \, \% {\text{ of black bean}}} \right)}}{100} \hfill \\ \end{array}$

Source: http://www.ndsu.edu/ndsu/goswald/chem117/labs/IsotopeLab.pdf

Worksheet III

Average Atomic Mass

• 1. The chemistry score (100 points in total) divided into three part; 50 points for test, 25 points for experiment, and 25 points for homework. Aree got 85 % from test, 77 % from experiment, and 91 % from homework, what is Aree’s chemistry score?

• 2. What is the average atomic mass of Silicon

  Isotope	Atomic Mass	Percent in nature
  Silicon-28	27.98	92.21
  Silicon-29	28.98	4.70
  Silicon-30	29.97	3.09

• 3. Carbon has two isotopes which are C-12 and C-13. The atomic mass of C-12 and C-13 are 12.000 and 13.003, respectively. If the average atomic mass of carbon is 12.011 what is the ratio of each isotope?

• 4. The results from mass spectrometer indicated that Ar composted of three isotope which are ${}_{18}^{36} {\text{Ar}}$, ${}_{18}^{38} {\text{Ar}}$, and ${}_{18}^{40} {\text{Ar}}$. The amount of each isotope is 0.1, 0.3, and 99.6 %, respectively. What is the average mass of Ar?

Isotope Demonstration

Objective: Explain the meaning and determine atomic number and atomic mass of isotope of element

Material: Red balls, Green balls, round-bottom flask, periodic table

Procedure:

• 1. Tell students that using red ball represents proton, and green balls represent neutron, and round- bottom flask is a nucleus of atom

• 2. Ask students “what word represent number of proton?” and “how the number of proton important?”

• 3. Put one red ball in a flask, ask students “what element that the model represents?” and “what is atomic mass, and atomic number?” (Hydrogen; 1; 1)

• 4. Add two green balls, “what happen to this model, still be the same element? Why?,” and “what is the symbol of this?” (${}_{1}^{3} H$)

• 5. Add one red ball, “what happen to this model, still be the same element? Why?,” and “what is the symbol of this?” (${}_{2}^{4} He$)

• 6. Add more balls and ask the students to make sure that they understand about atomic mass, atomic number, and isotope.

Student’s Journal

• 1. What did you learned from this class?

• 2. Any question do you have?

• 3. Could you apply what you learned to your daily life, how?

• 4. What activities do you like the most?

• 5. What activities you do not like?

• 6. Any comment and suggestion about the teaching and learning

Appendix B

Chemical Kinetics

This experiment focuses on the kinetics of acid–base reactions. The concept of chemical kinetics of this reaction is often taught in secondary or tertiary education levels. Whilst concrete which buildings are made of is chemically different to calcium carbonate, the overall idea is similar in that acids destroy carbonates—and this experiment uses materials that are a bit easier for us to handle in the laboratory class. Acids such as hydrochloric acid (HCl) will react quickly with calcium carbonate to produce a salt, water and release gaseous carbon dioxide. Other acids such as the acids present in vinegar also react with carbonates.

The reaction is: ${\text{CaCO}}_{3} \left( {\text{s}} \right) + 2{\text{HCl}} \left( {\text{aq}} \right) \to {\text{CaCl}}_{ 2} \left( {\text{aq}} \right) + {\text{H}}_{ 2} {\text{O}}\left( {\text{l}} \right) + {\text{CO}}_{ 2} \left( {\text{g}} \right)$

In the reaction above, how the acid and carbonate react may depend on a number of factors which we want you to investigate. Things you can consider are: the concentration of the acid, the particle size of the carbonate, the temperature of a reaction, and any other factors you can think of. This chemical equation can be applied to determine the rate of a reaction by plotting the relationships between the production of carbon dioxide over time. The experiment is first-order in its kinetics with respect to calcium carbonate and acid. The experimental data from kinetics investigations can be analyzed using Microsoft Excel Solver.

Inquiry-Based Learning

Teachers indicate the students a POE in an inquiry-based experiment in teaching and learning chemical kinetics: acid–base reactions. The use of a POE focuses on the student's understanding of a laboratory. Students need to practice using the ideas themselves to gain the ways of thinking by requiring written responses for this experiment. Students are given to design the experiment for studying how variables affect the rate of a reaction.

Prediction-Observation-Explanation

Prediction-Observation-Explanation, POE, probes student understanding by requiring students to carry out three tasks. It is most important to ensure that students are being asked to make a POE. In the whole classes, students have to:

• predict the outcome of some events, and justify reasons students have to support their prediction,

• describe what students see when the reaction occurs while doing the experiment, students have to write down their observation, and

• reconcile any conflict between what students predicted and what students observed.

Example: Predict how the surface of solid reactant, calcium carbonate, might affect the rate of a reaction, when we change the particle size from either

$\square$ small particle sizes to larger particle sizes

or

$\square$ large particle sizes to smaller particle sizes.

Prediction: When reacting with the same concentration of acid at the same temperature:

$\square$ the rate of a reaction increases

$\square$ the rate of a reaction decreases

$\square$ the rate of a reaction does not change.

Explanation for Prediction:

Observation:

Reconciliation of Prediction and Observation:

The experimental design used in this class of inquiry-based learning seeks to enhance students processes of scientific inquiry and to enhance their understanding of chemical kinetics. Here we use POE activities in this laboratory class in combination with several other tools. First is argumentation and argumentative practice. This means each students needs to defend or ague for the rightness of his or her predictions, observations, and explanations. This type of activity is a central activity of scientists and is used within research groups, in this experiment your assigned group. Here we emphasize the knowledge of chemical kinetics by sharing individual ideas between teachers and students in the groups.

Argumentation

The rationale of argumentation in this study is the contribution of the scientific arguments to the construction of scientific knowledge. The arguments can be seen to take place as an individual activity, through thinking and writing, or as a social activity to take place within a group, a negotiated social act within a specific community. The question that needs to be asked is not only what phenomenon is, but also how it related to events, and why it is important. The classroom practice does provide the opportunity to develop student's abilities to construct arguments. It is important to ensure that all students are asked to:

• indicate both the prediction of the outcomes and provide reasons to support the prediction.

• explore what happened, when the reaction occurs. All students have to write down their individual observations based on some personal reasoning.

• explain what happened, when students change variables which affect the rate of a reaction for studying chemical kinetics.

• discuss in your group, for example, students represent individual idea for few minutes through promoting appropriate classroom activities. Students might gain confidence in a deep understanding of knowledge.

Importance of Group Work

The teaching and learning approach in this experiment places emphasis on the discussion or argumentation described above in group work for promoting the negotiation and argument in order to develop the student's conceptual understanding. Teachers here in this experiment will try to encourage students to predict, observe, and explain what they are doing in the experiment in a group setting as well as in whole-class discussion. In the whole laboratory classes, students are also given the opportunity dealing with a particular problem in a group work.

Appendix C

Study Basic Chemistry with Green Tea Beverages

Jankun et al. (1997)

Green tea contains phenolic compounds. The phenolic compounds in green tea are the four flavanol: epicatechin, epicatechin gallate, epigallocatechin, and epigallocatechin gallate. The total phenolic compounds have been determined by the Folin-Ciocalteu method. This is a colorimetric redox reaction that measures all phenolic compounds. The Folin-Ciocalteu reagent is a solution of polymeric complex ions formed from phosphomolybdic acid (H₃PMo₁₂O₄₀) and phosphotungstic acid (H₃PW₁₂O₄₀).

In an alkaline solution, which is adjusted by sodium carbonate solution to pH 10, phenol was dissociated to phenolate anion. Folin-Ciocalteu is reduced to blue complex during phenolic compound oxidation. The absorption is measured at 760 nm.

$$ {\text{phenol }} + {\text{ Na}}_{ 2} {\text{CO}}_{ 3} + {\text{ FC reagent }} \to {\text{blue complex}} $$

The procedure is used to measure the relative phenolic compound contents in green tea, using gallic acid as a standard. The results are typically expressed as gallic acid equivalents (GAE).

Purpose

For this experiment, the objectives are:

• 1. To study the dilution method and the concentration of solutions;

• 2. To study the calibration curve; and

• 3. To determine the total phenolic compound in green tea beverages by UV–Vis spectrometer.

Materials and Reagents

For this experiment, the materials and reagents are:

• 1. 25-, 50-, and 100-ml volumetric flask;

• 2. 5-ml cylinder;

• 3. ml pipette;

• 4. 100-ml beaker;

• 5. Spectronic 20;

• 6. Water bath;

• 7. Balance;

• 8. Gallic acid;

• 9. Sodium carbonate; and

• 10. Folin-ciocalteu reagent.

Experiment procedures:

Part A: Prepare standard solution and create a calibration curve

• 1. Make up 0, 50, 100, 150, and 200 ppm solutions of gallic acid from the 1000 ppm gallic acid stock solution.

• 2. Add 1.0 mL aliquot of each gallic acid standard solution into beakers No.1, No.2, No.3, No.4, and No.5; add the following in order to each beaker:

  • 5 mL of 10 %v/v FC reagent and wait 3 min

  • 2 mL of 15 %w/v Na₂CO₃

• 3. Incubate the mixed solution for 15 min at 50 °C and transfer to 25-mL volumetric flask. Adjust the volume to exactly 25 mL with distilled water.

• 4. Record the UV absorbance at 760 nm by Spectronic 20.

• 5. Create a calibration curve with 0, 50, 100, 150, and 200 ppm gallic acid.

Part B-1: Determine total phenolic compound in green tea beverage sample

• 1. Filter the green tea beverage through paper and dilute to 10 % with water.

• 2. Add 1.0 mL aliquot of sample solution into beakers No.1, No.2, and No.3 and add the following in order to each beaker:

  • 5 mL of 10 % v/v FC reagent and wait 3 min

  • 2 mL of 15 % w/v Na₂CO₃

• 3. Incubate the mixed solution for 15 min at 50 °C and transfer to 25-, 50-, and 100-mL volumetric flasks, and adjust volume to exactly 25, 50, and 100 ml with distilled water.

• 4. Record the UV absorbance at 760 nm by Spectronic 20.

Part B-2: Determine total phenolic compound in green tea beverage sample

• 1. Filter the green tea beverage through paper and dilute to 10 % with water.

• 2. Add 1.0, 2.0, and 3.0 ml aliquot of sample solution into beakers No.4, No.5, and No. 6 respectively, and add the following in order to each beaker:

  • 5 ml of 10 % v/v FC reagent and wait 3 min

  • 2 ml of 15 % w/v Na₂CO₃

• 3. Incubate the mixed solution for 15 min at 50 °C and transfer to 25 mL volumetric flask and adjust volume to exactly 25 mL with distilled water.

• 4. Record the UV absorbance at 760 nm by Spectronic 20.

Calculation

Laboratory report

Study Basic Chemistry with green tea beverages

—————————————————————

Part A: Prepare standard solution and create a calibration curve

• 1. Make up a 0, 50, 100, 150, and 200 ppm gallic acid solution from 1000 ppm gallic acid, and record the information in the table below.

  	0 ppm	50 ppm	100 ppm	150 ppm	200 ppm
  Volume of 1000 ppm gallic acid (mL)
  Volume of solutions (mL)

• 2. Create and draw a calibration curve, using the information in the table below (Fig. A.1).

  Fig. A.1

  

  Gallic acid calibration curve

Notes

…………………………………………………………………………………………………………….. ……………………………………………………………………………………………………………..

Part B - 1: Determine total phenolic compound in green tea beverage

	10 % sample (ml)	10 % FC (ml)	15 % Na2CO3 (ml)	Vtot (ml)	A	C ppm of GAE
Beaker No.1	1.00	5	2	25
Beaker No.2	1.00	5	2	50
Beaker No.3	1.00	5	2	100

1. * V _tot Total of solution volumes

Notes……………………………………………………………………………………………………………..

Part B - 2: Determine total phenolic compound in green tea beverage

	10 % sample (ml)	10 % FC (ml)	15 % Na2CO3 (ml)	Vtot (ml)	A	C ppm of GAE
Beaker No.4	1.00	5	2	25
Beaker No.5	2.00	5	2	25
Beaker No.6	3.00	5	2	25

1. * V_tot = Total of solution volumes

Notes……………………………………………………………………………………………………………..

Calculation

Part B - 1 Determine total phenolic compound in green tea beverage sample

1.1 Beaker No.1

(1) What is the equivalent concentration of total phenolic compound in the blue solution measured by Spectronic 20?

(2) What is the equivalent amount of total phenolic compound in 25 ml of the blue solution?

(3) What is the equivalent amount of total phenolic compound in 1 ml of 10 % green tea beverage?

(4) What is the equivalent amount of total phenolic compound in 100 ml of 10 % green tea beverage?

5) What is the equivalent amount of total phenolic compound in 10 ml of green tea beverage?

(6) What is the equivalent concentration of total compound in 500 ml of green tea beverage sample?

1.2 Beaker No.2

(1) What is the equivalent concentration of total phenolic compound in the blue solution measured by Spectronic 20?

(2) What is the equivalent amount of total phenolic compound in 25 ml of the blue solution?

(3) What is the equivalent amount of total phenolic compound in 1 ml of 10 % green tea beverage?

(4) What is the equivalent amount of total phenolic compound in 100 ml of 10 % green tea beverage?

(5) What is the equivalent amount of total phenolic compound in 10 ml of green tea beverage?

(6) What is the equivalent concentration of total compound in 500 ml of green tea beverage sample?

1.3 Beaker No.3

(1) What is the equivalent concentration of total phenolic compound in the blue solution measured by Spectronic 20?

(2) What is the equivalent amount of total phenolic compound in 25 ml of the blue solution?

(3) What is the equivalent amount of total phenolic compound in 1 ml of 10 % green tea beverage?

(4) What is the equivalent amount of total phenolic compound in 100 ml of 10 % green tea beverage?

(5) What is the equivalent amount of total phenolic compound in 10 ml of green tea beverage?

(6) What is the equivalent concentration of total compound in 500 ml of green tea beverage sample?

Part B - 2 Determine total phenolic compound in green tea beverage sample

2.1 Beaker No.4

(1) What is the equivalent concentration of total phenolic compound in the blue solution measured by Spectronic 20?

(2) What is the equivalent amount of total phenolic compound in 25 ml of the blue solution?

(3) What is the equivalent amount of total phenolic compound in 1 ml of 10 % green tea beverage?

(4) What is the equivalent amount of total phenolic compound in 100 ml of 10 % green tea beverage?

5) What is the equivalent amount of total phenolic compound in 10 ml of green tea beverage?

(6) What is the equivalent concentration of total compound in 500 ml of green tea beverage sample?

2.2 Beaker No.5

(1) What is the equivalent concentration of total phenolic compound in the blue solution measured by Spectronic 20?

(2) What is the equivalent amount of total phenolic compound in 25 ml of the blue solution?

(3) What is the equivalent amount of total phenolic compound in 1 ml of 10 % green tea beverage?

(4) What is the equivalent amount of total phenolic compound in 100 ml of 10 % green tea beverage?

(5) What is the equivalent amount of total phenolic compound in 10 ml of green tea beverage?

(6) What is the equivalent concentration of total compound in 500 ml of green tea beverage sample?

2.3 Beaker No.6

(1) What is the equivalent concentration of total phenolic compound in the blue solution measured by Spectronic 20?

(2) What is the equivalent amount of total phenolic compound in 25 ml of the blue solution?

(3) What is the equivalent amount of total phenolic compound in 1 ml of 10 % green tea beverage?

(4) What is the equivalent amount of total phenolic compound in 100 ml of 10 % green tea beverage?

(5) What is the equivalent amount of total phenolic compound in 10 ml of green tea beverage?

(6) What is the equivalent concentration of total compound in 500 ml of green tea beverage sample?

Conclusions