Supporting Knowledge Integration in Chemistry with a Visualization-Enhanced Inquiry Unit

Abstract

This paper describes the design and impact of an inquiry-oriented online curriculum that takes advantage of dynamic molecular visualizations to improve students’ understanding of chemical reactions. The visualization-enhanced unit uses research-based guidelines following the knowledge integration framework to help students develop coherent understanding by connecting and refining existing and new ideas. The inquiry unit supports students to develop connections among molecular, observable, and symbolic representations of chemical reactions. Design-based research included a pilot study, a study comparing the visualization-enhanced inquiry unit to typical instruction, and a course-long comparison study featuring a delayed posttest. Students participating in the visualization-enhanced unit outperformed students receiving typical instruction and further consolidated their understanding on the delayed posttest. Students who used the visualization-enhanced unit formed more connections among concepts than students with typical textbook and lecture-based instruction. Item analysis revealed the types of connections students made when studying the curriculum and suggested how these connections enabled students to consolidate their understanding as they continued in the chemistry course. Results demonstrate that visualization-enhanced inquiry designed for knowledge integration can improve connections between observable and atomic-level phenomena and serve students well as they study subsequent topics in chemistry.

Appendices

Appendix 1

Outline of Chemistry Scene Investigators curriculum unit.

Activity 1:

This activity introduces students to the WISE interface and to the context of the unit. The activity begins by explaining the greenhouse effect with animations, then by “traveling back in time” to collect sample data of carbon dioxide from different years. Students use WISE to graph their collected data, make comparisons to scientific data, and make predictions based upon their data.

Activity 2:

Students manipulate a Molecular Workbench simulation of a combustion reaction, adding and removing heat. Embedded prompts ask students to describe their observations. The students revisit the same simulation of the same combustion reaction with numerical and graphical outputs of molecular concentration. Students investigate the relationships between the chemical reaction and the ratios of molecules involved. Embedded prompts then ask students to explain how the graphs and simulations relate to the balanced equation for the reaction, and also ask students to identify what aspects of a chemical reaction the balanced equation does not represent.

Activity 3:

Students learn about water vapor and methane as greenhouse gases and then manually form these chemicals by breaking and creating bonds and molecules with Molecular Workbench. The activity ends with a similar exercise of atom manipulation to introduce the concept of limiting reactants. Embedded prompts ask students to make connections between their actions in these simulations and chemical reactions, balanced equations, and limiting reactants.

Activity 4:

The fourth activity elicits students’ strategies used while numerically balancing equations, and then asks students to reflect on these strategies after going through an interactive hydrocarbon equation exercise. Students also read about carbon dioxide as a greenhouse gas and compare these three greenhouse gases they have learned. At the end of the unit, students have to decide how to allot research funding for these three greenhouse gases, based on the information they have learned and the chemistry concepts they have seen throughout the curriculum. Students put their arguments up on an online discussion board for other groups to critique and compare ideas.

Appendix 2

Appendix 3

Targeted ideas and scoring rubrics for pretests and posttests.

Targeted ideas

• 1. Students connect molecular and symbolic representations of chemical equations

  • 1.1. Student demonstrates understanding of coefficient within a chemical formula on a molecular scale, recognizes the coefficient represents total number of molecules

  • 1.2. Student demonstrates understanding of subscript within a chemical formula on a molecular scale, recognizes that subscripts represent the number of atoms within a molecule

  • 1.3. Student demonstrates understanding of the total number of atoms as represented by the chemical formula, but not the structure that the chemical formula represents (i.e., students confuse H₄O₂ with 2H₂O)

• 2. Students understand conservation of mass in chemical reactions

  • 2.1. Student demonstrates understanding that the total number of atoms in the reactants have to equal the total number of atoms in the products in a chemical reaction

• 3. Students understand the dynamic and interactive aspect of a chemical reaction

  • 3.1. Student demonstrates understanding that a chemical reaction is a process of bond breaking and bond formation

• 4. Students understand the quantitative aspects of a chemical reaction

  • 4.1. Students can balance equations in traditional math representations

• 5. Students understand limiting reagents on a molecular scale

  • 5.1. Student demonstrates understanding of limiting and excess reactants in a reaction

• 6. Students understand energy and chemical reactions

  • 6.1. Student demonstrates understanding of the relationship between temperature and molecular speed.

  • 6.2. Student demonstrates understanding of the relationship between heat and reaction rate.

Item 1. Targeted ideas to integrate: 1.1 coefficients, 1.2 subscripts, 1.3 total number of atoms, 2.1 conservation of mass

Score	Description	Example
5	Systemic link—all concepts integrated and correctly applied, with no alternative answers	CH4 + 2O2 → CO2 + 2H2O
4	Complex link—two or more scientifically valid links among ideas	CH4 + O2 → CO2 + H2O
3	Full link—connects two ideas, with partial understandings of others	CH4 + 4O → CO2 + H4O2
2	Partial link—partial connections among ideas, students consider relevant ideas but not consistent throughout response	CH4 + 4O → C + 2O + 2H2O
1	No link—students have relevant but non-normative links or ideas	H2O
0	No answer/irrelevant

Item 2. Targeted ideas to integrate: 1.1 coefficients, 1.2 subscripts, 1.3 total number of atoms 2.1 conservation of mass

Item 3. Targeted ideas to integrate: 1.1 coefficients, 1.2 subscripts, 1.3 total number of atoms

Score	Description	Example
4	Complex link—connects all three concepts and chemical formula	“Figure A shows 2NO molecules, and Figure B shows a NO2 molecule. The difference is that in figure A, there are 2 N atoms and 2 O atoms, whereas in figure B, there is only one N atom and 2 O atoms. This is represented by a 2 as a coefficient in figure A and a subscript for oxygen in Figure B”
3	Simple link—connects two ideas (and chemical formula). Possible partial connection to other knowledge	Correct formula and number of atoms: “Figure A shows 2NO molecules, and Figure B shows a NO2 molecule. The difference is that in figure A, there are 2 N atoms and 2 O atoms, whereas in figure B, there is only one N atom and 2 O atoms.”
		Correct formula and use of subscripts/coefficients: “Figure A shows 2NO molecules and Figure B shows a NO2 molecule. The difference is that the 2 is a coefficient in figure A and a subscript in figure B.”
2	Partial link—understanding of one idea and possible partial understandings of other concepts	Chemical formula: “Figure A is 2NO and Figure B is NO2”
		Subscripts and Coefficients: “Figure A has 2 for a coefficient and Figure B has 2 for a subscript”
		# of atoms: “The difference is that figure A has 2 N atoms and 2 O atoms, and figure B has 1 N atom and 2 O atoms.”
		Correct formula, incorrect subscript or coefficient: “Figure A is 2NO and Figure B is NO2. Figure A shows a subscript and Figure B shows a coefficient”
		“Figure A is N2O2 and Figure B is NO2. The difference is that A has 2 N atoms and B has only one.”
1	No link—students have relevant but non-normative links or ideas	“Figure A is a subscript and Figure B is a coefficient”
		“Figure A is N2O2 and figure B is NO”
0	No answer

Item 4. Targeted ideas to integrate: 1.1 coefficients, 1.2 subscripts, 1.3 total number of atoms

Item 5. Targeted ideas to integrate: 1.1 coefficients, 1.2 subscripts, 2.1 conservation of mass, 4.1 balancing equations

Score	Description	Example
4	Complex link—connects three or more ideas (e.g., recognizes balanced equation is wrong, provides correct balanced equation and an explanation involving conservation of mass)	“Chemie is wrong, Chemie has different numbers of atoms in either side of the equation. The correct equation is 2H3PO4 + 3 Mg(OH)2 → Mg3(PO4)2 + 6H2O”
3	Simple link—connects two ideas with possible partial understanding of others (e.g., recognizes balanced equation is wrong and only provides correct balanced equation)	“Chemie is wrong, Chemie has too many P atoms on the right side of the equation”
		“Chemie is wrong. The correct equation is 2H3PO4 + 3 Mg(OH)2 → Mg3(PO4)2 + 6H2O”
2	Partial link—demonstrates understanding of one idea with possible partial understandings of other ideas (recognizes balanced equation is wrong, gives alternative explanation)	“Chemie is wrong. The correct equation is 2H3PO4 + 3 Mg(OH)2 → 4Mg3(PO4)2 + 2H2O”
1	No link—partial use of one concept (e.g., does not recognize balanced equation is wrong or states wrong with no explanation)	“Chemie is right”
		“Chemie is wrong”
0	No answer/irrelevant

Item 6. **Non-KI item Targeted ideas: 2.1 Conservation of mass, 4.1 Balancing equations

Score	Description	Student example
3	Correct answer—correct balanced equation and number of atoms on each side	2C2H6 + 7O2 → 4CO2 + 6H2O, Products: C = 4, H = 12, O = 14 Reactants: C = 4, H = 12, O = 14
2	Partially correct—incorrectly balances equation but has same number of atoms on each side	2C2H6 + 4O2 → 4CO2 + 6H2O, Products: C = 4, H = 12, O = 14 Reactants: C = 4, H = 12, O = 14
1	Incorrect—incorrect balanced equation and different number of atoms on each side	2C2H6 + 4O2 → 4CO2 + 6H2O, Products: C = 4, H = 12, O = 8 Reactants: C = 4, H = 12, O = 14
0	No answer

Item 7. Targeted ideas: 1.1 coefficients 1.2 subscripts, 2.1 conservation of mass, 3.1 dynamic nature of a reaction, 5.1 limiting and excess reactants

Item 8. Targeted ideas to integrate: 3.1 dynamic aspects of reactions, 6.1 temperature and molecular speed, 6.2 heat and reaction rate

Score	Description	Example
4	Complex link—two or more scientifically valid links among ideas	“When heat is added, the molecules move around faster and causes the bonds to break and form an increased rate, which then increases reaction rate”
3	Full link—valid link between two scientifically relevant concepts, with partial understandings of others	“When you add heat to the reaction, the molecules move faster and the bonds break”
2	Partial link—one scientifically valid idea, and possible partial understandings of others	“When you add heat, the molecules move around more”
1	No link—students have relevant but non-normative links or ideas	“The molecules have more heat”
0	No answer/irrelevant