Summary

In this lesson, students will create an initial model of an atom (using various food items) drawing from the knowledge that they brought into the class. They will then use the same materials to work through an interactive note-taking lesson on how the model of the atom evolved over time. Having completed the interactive notes, the students return to their original models and adjust as needed.

Grade Level

High School

NGSS Alignment

This lesson will help prepare your students to meet the performance expectations in the following standards:

• MS-PS1-1: Develop models to describe atomic composition of simple molecules and extended structures.
• Scientific and Engineering Practices:
  • Developing and Using Models

Objectives

By the end of this lesson, students should be able to:

• Construct a model of the atom that is accepted in science today.
• Compare and contrast the different models of the atom that have been developed throughout history.
• Compare and contrast the size, location, and charge of the different subatomic particles.

Chemistry Topics

This lesson supports students’ understanding of:

• Atomic theory
• Models of the atom
• Subatomic particles

Time

Teacher Preparation: 10 minutes
Lesson: 60 minutes

Materials (per student)

• Student handout
• Computer and projector with volume, or student device to access video
• A piece of paper towel
• Regular Marshmallows
• Mini Marshmallows (white)
• Mini Marshmallows (colorful)
• Mini Chocolate chips (It is important that they are mini.)
• Froot Loops (generic is fine)
• Other food items as you desire

Safety

• Do not consume lab solutions, even if they’re otherwise edible products.
• Food in the lab should be considered a chemical not for consumption.

Teacher Notes

• This lesson could be done as a first introduction to atomic structure, or it could be used after students have been taught the basics of the charges and locations of the subatomic particles. This information is presented briefly in the PowerPoint, but for some students, it might be helpful to have a more thorough introduction before introducing it in this lesson.
• For this lesson, I put the students in pairs or small groups (no more than 4 per group) and send them to tables or lab stations that have a variety of food items on them. The food items I use are marshmallows, mini marshmallows (both the original white and the colored kind), mini chocolate chips, and froot loops, though you could include others as well. Each group should have around a handful of each. These do not need to be specifically counted.
  • Please note that if you wish to allow students to eat the food items at the end of the lesson, this activity should not be conducted in a lab setting. Also, consult with the school nurse and be aware of possible food allergies when using food items in class.
• The objective of the first part of this lesson is to have them establish their current thoughts on what the atom looks like based on their pre-existing knowledge. It is very important that the students do not have access to technology at this point. They need to come up with their own ideas (a little investment learning) in order to make the lesson meaningful. The only instruction that they receive (besides what is on the student sheet) is that they are to construct a model of an atom (just a general atom, nothing specific) using the materials that they have. I give them five minutes to build the model in their group, and then another five minutes to write their explanation and sketch their model on the handout. If time allows, you can have students share their models with the class, and/or submit an image of their model via email, dropbox, your learning management system, etc.
• Next, the students return to their individual seats with a paper towel and some of each of the food items so they can use them to create various historical atomic models.
• At this point, I present a short PowerPoint introducing the ideas of scientific theory, models, and subatomic particles. There are some additional notes in the “notes” section of some of the PowerPoint slides that may be helpful to review before presenting to students. Students answer a few questions on the handout using information from the presentation.
• Then we watch this video to walk them through the history of atomic theory and the different models that have led us to where we are today. It starts with the ancient Greeks and progresses through Dalton’s model, the Plum Pudding model, the nuclear model, the Bohr model, finishing up with the modern Quantum Mechanical model. As we work through each model, the students move their food to show the model on their individual desks. I recommend pausing the video for a few minutes between models to allow students to sketch their food models and make notes on the student handout. You may want to have the class say what their “important notes” were at the end of each model to make sure everyone is on the same page.
  • Alternatively, you could have students watch the video on their own devices with headphones so they could watch it at their own pace and pause it when necessary. If you do this, I recommend allowing students to discuss it in pairs or small groups once they’ve finished and then having a full class discussion about what they watched.
• The interactive modeling with food engages the students in a different way than just note-taking. After the lesson, I provide the link to the video so students can re-watch it if they need to review it.
• As a closer, the students return to their groups and they adjust their original models of the atom using the knowledge that they have now. They can also begin to answer the analysis part of the student sheet.
• This lesson is very useful as an anchoring activity. It is easy to circle back to this lesson when we talk more about the size of neutrons, protons, and electrons as well as the locations of each. It is great when we start to talk about bonding as well.
• In the beginning, there are no right answers, but by the end of the lesson, the students should be able to accurately place each subatomic particle in the correct location of the general atom.  The number of each isn’t stressed, but rather the location (and with that, the size) of the particles.
• If you want to go into more detail on the experiments that led scientists to each development in atomic theory, you could also watch or assign the following videos on the discovery of the electron with the cathode ray tube experiment, the discovery of the positively charged nucleus with the gold foil experiment, and the discovery of neutrons.
• Related classroom resources from the AACT library that may be used to further teach this topic:
  • Lab: Investigating the Sizes of Atomic Particles
  • Project: The Scientists Behind the Atom
  • Project: Element Project
  • Simulation Activity: Building an Atom
  • Activity: Atomic Structure RAFT
  • Activity: Bohr Model vs. Quantum Mechanical Model
  • Demonstration: The Hoopla about Atoms
  • Lesson Plan: Acting Out Atomic Structure
  • Video Collection: Founders of Chemistry