SWBAT describe how and why atomic theory changes over time.

Atomic theory is a great example to help students realize why we use models to help us understand atoms and how ideas change with new evidence.

Chocolate chip cookie atoms? Yum! Atomic theory has advanced over time with increased understanding of atomic structure that comes from evidence generated from experimentation. This lesson can stand alone, but also works in conjunction with Black Box Problems - Modeling the Unobservable and Collecting Data: Observation and Inference.

While this lesson references atomic structure (Matter and Its Interactions Core Disciplinary Idea: students model simple molecules and extended structures (**MS-PS1-1**), it also provides opportunity for students to practice science skills such as developing models to describe unobservable mechanisms (**SP2**), consideration of limitations of data analysis in order to improve precision and accuracy of data with better technological tools and methods (**SP4**) and communication of scientific and technical information in writing and through oral presentations after critically reading scientific texts to obtain scientific information to describe evidence about the natural and designed worlds (**SP8**).

In addition to these practices, the cross cutting concept that provides cohesion to this lesson is: Complex and microscopic structures and systems can be visualized, modeled, and used to describe how their function depends on the shapes, composition, and relationships among its parts; therefore, complex natural and designed structures/systems can be analyzed to determine how they function (**CCC**). This cross cutting concept is revisited during this lesson as students research to discover how atomic theory changes over time in light of new evidence.

Through the practice of obtaining, evaluating and communicating information about an element, students also meet several Common Core English Language Arts Standards for Writing:

CCSS.ELA-Literacy.WHST.6-8.7 Conduct short research projects to answer a question (including a self-generated question), drawing on several sources and generating additional related, focused questions that allow for multiple avenues of exploration.

CCSS.ELA-Literacy.WHST.6-8.8 Gather relevant information from multiple print and digital sources, using search terms effectively; assess the credibility and accuracy of each source; and quote or paraphrase the data and conclusions of others while avoiding plagiarism and following a standard format for citation.

This project is a research-based inquiry investigation including multiple lessons taught over the span of 1 week. To help manage the magnitude of this project, you will find the project split into 2 parts.

20 minutes

In order to ENGAGE students in this lesson, students view this image (or real cookies, to make it more engaging and enticing!):

As students view the image, they complete a series of "think-pair-share" rotations using the following prompts:

**1) How does this cookie represent a model of an atom?**

**2) Does this cookies represent a complete model? Why or why not?**

**3) What are the limitations of this model?**

**4) Does this model represent what we believe atoms are like today? What would need to be different?**

Depending on the level of students' background knowledge, a range of responses can be expected. These responses illuminate how much structure students may need in the following stages of this lesson. The important learning piece from this engagement activity is to encourage students to start thinking about atomic models, how models have limitations and that models can be modified when new evidence is presented. If students need additional instruction around models, use this lesson (or parts of this lesson) to fill in the gaps in understanding: Black Box Problems - Modeling the Unobservable. This presentation provides an outline for this lesson (and additional instruction around models) as well: Black Box Problems and Atomic Theory Presentation.

80 minutes

The EXPLORE stage of the lesson is to get students involved in the topic so that they start to build their own understanding. To help students explore the ideas related to evolving atomic theory, students conduct a short research project guided by the following question:

**How has our understanding of atoms changed over time?**

Students will use the information they find to create a timeline of atomic theory. Showing students an example of completed notes: Let's Get Atomic Student Research and a completed timeline gives students a clear view of the final product. For more on using exemplars and providing structure to avoid learning pitfalls, visit this section's reflection. Scientific research and access to technical texts presents challenges to students. Therefore, there are resources provided for several levels of scaffolded support. There are four approaches, with different levels of support, here:

1) Students conduct their own research project using any resources or note-taking tools they would like to use in order to answer the guiding question.

2) Students use the Let's Get Atomic! Student Research Organizer to research using uncurated online texts. This approach requires students to find and analyze texts to ensure source reliability and accuracy. The graphic organizer provides structure for the research, so that students are guided toward finding information that is shows how atomic models have changed over time due to new evidence.

3) A third level of support can be provided where students use a curated text: Let's Get Atomic! Atomic Theory Curated Research Text and the Let's Get Atomic! Student Research Organizer or the Let's Get Atomic! Interactive Student Research Notes. This more structured approach provides students with the information needed to complete the research. Students use either the graphic organizer or the interactive research notes to record their information.

4) The most structured way for students to conduct research is by using the Black Box Problems and Atomic Theory Presentation to conduct research, which is modeled and guided by an expert (teacher or student):

**Teacher Note: **Here are several informative support resources to direct students toward during their research:

Atomic Theory Resource Page

Visual Infographic of Atomic Theory

History of Atoms Video

Continue on to Part 2 for the EXPLAIN, EXTEND and EVALUATE components of this lesson; Time: 3-5 50-minute lessons or equivalent block periods.