“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.
The SAMM survey was developed by the ACCT team (indicated by the star). How Sweet it is, Solutions and Concentration, and Perfume Smells were developed by past ACCT cohort members.
The Structure and Motion of Matter (SAMM) survey is a 15-minute, open-ended formative assessment tool that probes how students think about the structure and dynamics of a gaseous mixture. It has been tested in middle school, high school, and university chemistry classes, in both English and Spanish.The SAMM survey presents three scenarios that involve a perfume or other scented volatile substance being released on one side of a room and detected by a nose on the other side of the room. Students are asked to draw how the perfume and air molecules behave, and explain in writing both the molecules’ behavior and why they behave this way.
This formative assessment investigates student ideas regarding chemical identity through writing about solution concentration. This formative is an easy way to get students interested in the topic of concentration because making juice is accessible to all learners. By asking students to think about a strategy for making juice of a desired sweetnesw and explain why that strategy works, followed by drawing particle pictures to compare the juices, students should be able to think more critically and reveal their chemical thinking. Since the concept of concentration had not been taught yet, the words “sweet” and “less sweet” are used in place of the words concentrated and dilute. In the formative assessment, Nassir prefers the taste of sweet juice (dark red) and his Mom prefers it to be less sweet (lighter red color).
The Solutions and Concentration formative assessment task asks students to figure out what concentration means by comparing three solutions that they make. This formative assessment targets structure-properties relationships because it intends to explore students’ thinking about what makes solutions behave differently by focusing on the process of dissolution and the meaning of concentration.
The Perfume Smells formative assessment task asks students to identify trends in the ingredients of perfumes and developing connections between scents and chemical structure. This formative assessment targets structure-property relationships by getting students to think about how properties of the molecule, including scent, are determined by molecular structure. Students will share their thinking about how functional groups can be predict the smell of organic compounds. In Part 1, students have to process that the overall smell in a perfume or cologne may be due to many of the molecules present in the cologne. In Parts 2 and 3, students will need to understand that molecules often have many functional groups, which can sometimes have conflicting smells to them (such as sweet, minty, and fishy), and then they will have to predict how these molecules will behave.