ACCT | Chemical Education Xchange

ACCT

Assessing for Change in Chemical Thinking (ACCT) is an NSF-funded, research-practice partnership focused on fostering chemical thinking in middle school, high school, and undergraduate science classrooms using formative assessment strategies. ChemEd X has partnered with ACCT to disseminate the program materials, as it aligns with their mission of making digital chemistry teaching content and resources accessible. We encourage you to explore the ten session professional development series, (including facilitation guides, slides, and resources). In addition, the blog posts on formative assessments and the core program elements are accessible through the ChemEd X platform, free of charge. For inquiries, please contact ACCT at ACCTProject@umb.edu

Our collection here on ChemEd X includes:

Resources for doing formative assessment in the classroom

Studying how teachers enact formative assessment

Analyzing how students use chemical thinking

Information about our group

Relevant publications

Together with ChemEd X, we strive to empower teachers of chemistry to Xplore, Xtend, and Xperience.

close up of teacher in front of first row of students

Resources for doing formative assessment in the classroom

Access formative assessments developed by the Sevian research group past ACCT cohort participants according to the chemical thinking questions that they uncover.

1. What types of matter are there?

“What types of matter are there?” is a question of classification. Classification is a very important tool for predicting and explaining the properties of substances in our surroundings. For example, classifying a material as a metal versus a nonmetal allows us to predict that it may conduct heat and electricity quite well. Similarly, identifying a substance as an ionic compound allows us to explain why its aqueous solution conducts electricity. Classifications are often loose categories with gray areas, but they support chemical thinking when seeking to synthesize new substances, determine the identity of a material, or control a chemical process.

2. What cues are used to differentiate matter types?

“What cues are used to differentiate matter types?” is a question of differentiation, or telling matter types apart. Differentiation in chemical thinking is based on the assumption that every chemical substance has at least one differentiating property that makes it unique. Good differentiating properties do not depend on the amount of substance under analysis and have unique values for different materials. Examples include boiling points, solubilities in water, and molecular structure. The characterization of these differentiating properties is critical for the design of methods to separate substances, identify them, detect them in our surroundings, or quantify their amounts.

3. What properties of matter types emerge?

“What properties of matter types emerge?” is a question of the origin of properties. Predicting or explaining properties of substances often requires analysis of structural rather than compositional aspects of substances, and involves reasoning about emergence rather than arguing based on a central cause. Explaining behaviors of substances involves examining what influences energetic stability and how behaviors on one distance scale emerge from dynamic interactions between structural components on a smaller scale. There are many different scales at which these structure-property relationships are built (from multiple entities in mixtures down to electronic structure). This chemical thinking question is often central to predicting properties of substances, e.g., which oil is best for lubricating a transmission or frying plantains or making soap.

4. How does structure influence reactivity?

“How does structure influence reactivity?” is a question of connection between chemical structure and behavior. The specific ways in which the submicroscopic particles of matter interact with each other and are transformed into different chemical species depend on their atomic composition and molecular structure. The types of atoms present in a molecule and their relative arrangement in space affect the distribution of the electrons that can participate in bonding processes with other particles. Understanding how molecular structure affects electron distribution, and how this in turn determines how different particles interact and react with each other is critical to design the synthesis of desired materials and to control chemical processes.

5. What drives chemical change?

“What drives chemical change?” is a question of why chemical processes happen. Chemical reactions occur to different extents and at different rates. To what extent reactants will be converted into products depends on the relative potential energy of their submicroscopic components as well as on the relative configurations these components can adopt. The speed of a process depends on the mechanism of the reaction and on the concentration of those species that limit the reaction rate. Both reaction extent and rate are affected by the temperature of the system. Understanding the drivers of chemical change is critical for predicting, explaining, and controlling processes of interest, from making soap to reducing pollution.

particulate level model of example chemical change

6. What determines the outcomes of chemical changes?

“What determines the outcomes of chemical changes?” is a question of dynamic behavior and probability. When the particles that make up different substances interact with each other, their interactions may lead to a variety of structural changes (e..g., some atoms may change positions or separate from a molecule). Which of these random changes are more likely to occur depends on the relative potential energy between the original particles and the new particles that are formed. More stable particles (with lower potential energies) are more probable to form and will determine the path and outcome of the reaction. Understanding the relationship between structure, stability, and reaction mechanism allows us to predict, explain, and control the products of chemical processes.

7. What interaction patterns are established?

“What interaction patterns are established?” is a question that involves selecting which classification systems and models are most relevant to understanding chemical processes for a particular purpose. Chemical reactions exhibit patterns that allow us to classify them in different groups to facilitate prediction, explanation, and control. Multiple classification systems and chemical models are often used simultaneously to analyze a process depending on the purpose and context. For example, a process may be thought of as a redox reaction when used in an electrochemical cell but as an addition reaction if used for synthetic purposes. Acid-base reactions can be understood by accounting for proton transfer or by paying attention to electron sharing. This chemical thinking question is often central to the analysis of chemical processes used to synthesize and analyze substances, and to harness chemical energy.

pictorial diagram showing how to perform reaction

8. What affects chemical change?

“What affects chemical change?” is a question of identification of internal and external variables that affect the extent and rate of chemical processes. The extent to which reactants are transformed into products and the rate at which the transformation occurs depend on internal factors such as the composition and structure of the particles involved and their concentration in the system, as well as on external factors such as temperature, pressure, and the nature of the environment in which the reaction takes place (e.g., type of solvent, pH). Identifying these factors and their effects on reaction extent and rate allows us to design and control chemical processes for particular purposes.

particulate level model of example of chemical change

9. How can chemical changes be controlled?

“How can chemical changes be controlled?” is a question that involves understanding how changes in conditions affect the relative stability of the species involved in a chemical process. Control can be achieved by selecting reactants with structural features that change their energetic stability, varying the concentrations of reactants or capturing and removing products, adding substances which react with intermediates to facilitate or inhibit different mechanistic steps, changing temperature to activate chemical species,, or choosing solvents that facilitate or inhibit certain interactions. For example, controlling the replication of a virus may involve tuning conformations of a substance involved in the replication to block one pathway in the process. This chemical thinking question is often central to chemical process design and analysis activities, such as improving solar cell operation, analysis of battery efficiency, or characterizing the degradation of a dye.