Learning Objective #2

Learning Objective 2:

Students will be able to use models to represent atoms and molecules before and after a chemical reaction and explain how the accuracy of their model in representing the types and number of atoms demonstrates the law of conservation of mass.

Concepts and Skills

Concept: Atoms and Molecules: Students need to understand that matter is composed of atoms, which can combine to form molecules. They should know that atoms of different elements have unique properties, and molecules are formed when they are chemically bonded.

Skill: Modeling: Students should be able to develop and use models (physical or digital) to represent atoms and molecules. This includes understanding that the models are simplified representations of reality and can be used to visualize and understand the rearrangement of atoms during chemical reactions

Formative Assessment Questions

Identify the building blocks that make up all matter.

Question 1 maintains a DOK level 1, asking students to recall basic knowledge but focusing on the fundamental particles that make up all matter.

Create a labeled diagram to represent a water molecule (H₂O). In your diagram, clearly show how the atoms are connected. Explain what each part of your model represents.

DOK Level: 2, Bloom's: Applying. Question 2 maintains DOK Level 2, requiring understanding, but focuses on atoms and their connections within the molecule, a key concept for MS-PS1-5.

A piece of wood is burned. Does the total number of atoms of wood disappear or are they rearranged? Explain your reasoning using the Law of Conservation of Mass.

DOK Level: 3, Bloom's: Analyzing. Question 3 maintains a DOK Level 3 and requires analytical thinking by asking students to apply the law of conservation of mass to explain the observed changes in matter during a chemical reaction.

Using a reaction of your choice, create a model that shows the conservation of atoms during a chemical reaction. You can use any material you like for the physical model or a drawing. Justify your model's design by explaining how it illustrates that the total number of atoms does not change during a chemical reaction. Then, describe a different type of model (digital or drawing) that could also be used to represent this concept.

DOK Level: 4, Bloom's: Evaluating. Question 4 maintains DOK level 4 by requires the creation of models. By having students justify their model using the Law of Conservation of Mass, this reinforces the key concepts. Finally, asking them to describe another model encourages higher-level thinking about representation.

Explanation

Alignment with MS-PS1-5: As per the standard, all questions align directly with the standard, emphasizing that the number of atoms is conserved during a chemical reaction. The assessment boundary (no atomic masses, balancing equations, or intermolecular forces) is also considered.

DOK Level Alignment: The questions are structured to match the complexity levels specified by the DOK levels.

Bloom's Taxonomy Alignment: Each question is designed to promote the cognitive process (remembering, applying, analyzing, evaluating) associated with the specified Bloom's level.

Focus on Atoms: The revisions emphasize atoms and their arrangement in molecules and reactions, directly relevant to the standard.

Modeling: The revisions explicitly require students to engage with the concept of modeling, either by drawing or creating a model, in alignment with the standard.

Emphasis on Justification: Question 4, require students to justify their model's design by explaining how it illustrates the conservation of mass/atoms, reinforcing understanding.

Anticipated Misconceptions & Remediation

Atoms Appear or Disappear in Chemical Reactions: Students might believe that atoms can be created or destroyed during a chemical reaction, rather than rearranged. This is often due to a lack of understanding of the conservation of matter.

Clarification: Emphasize the Law of Conservation of Mass, which states that matter (and thus the number of atoms) cannot be created or destroyed in a chemical reaction but can only change forms.

Activity Suggestion: Use manipulatives or drawings to represent atoms and molecules before and after a simple chemical reaction (e.g., hydrogen and oxygen combining to form water) to show that the number of atoms remains the same visually.

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