Summary

In this activity, students will answer questions while watching the video The World has a Receipt Problem from the Ingenious series produced by the American Chemical Society. Each episode investigates a different topic related to how leading-edge chemistry is taking on the world’s most urgent issues to advance everyone’s quality of life and secure our shared future. This episode investigates the process of thermal printing on receipts, and the limitations related to the paper that currently prints using leuco dyes. This heat-sensitive ink appears when it reacts with an acid developer embedded in the paper. Scientists are working to develop a new kind of thermal receipt paper, that can use the same printers, however, it offers many additional benefits and potential uses.

Grade Level

High School

Objectives

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

• Describe the current challenges with receipt paper.
• Provide a general overview of how a “heat-sensitive dye” works. 
• Briefly explain how the use of microspheres can be advantageous in the future of printing.
• Discuss the benefits related to the new three-layered thermal paper design—for both receipts and other products.

Chemistry Topics

This activity supports students’ understanding of:

• Energy & Thermodynamics
• Heats
• Physical Properties
• Physical Changes
• Molecular Structure
• Polymer
• Monomer

Time

Teacher Preparation: minimal
Lesson: 10-20 minutes

Materials

• Ingenious Video: The World has a Receipt Problem
• Student Handout
• Computer and projector with volume, or student device to access video

Safety

• No specific safety precautions need to be observed for this activity.

Teacher Notes

• The Ingenious video series spotlights stories from the frontlines of chemistry research and development, where passionate innovators are stepping up to confront problems like pollution, overfishing, sustainability, and personal safety.
• In this video, The World has a Receipt Problem, students will learn that the receipts you take home from the store (or stuff in your bag or lose in your car) employ a printing method that’s been around since the 1970s. Thermal printing involves heat-sensitive inks called leuco dyes that show up when they react with an acid developer embedded in the paper. Not only do these inks fade easily, but receipts that use them aren’t recyclable, and could even be dangerous to your health. Taking a cue from a failed experiment, scientists are developing a new kind of receipt paper that will use the same thermal printers without leuco dyes. Instead of acid developers, this paper is coated in reflective microspheres that collapse under heat, allowing regular ink underneath to show through.
• The running time of this video is about 5 minutes and 30 seconds. As it is a short video and it moves quickly, you may want to show it twice, or instruct students to pause the video as needed on their own devices to ensure that they can record answers to all of the questions.
• The student questions are presented in sequential order in the video.
• An answer key has also been provided for teacher reference.
• The final questions are reflection-based and might be helpful in prompting a class discussion after students have a few minutes to answer them independently.
• The AACT classroom resource library offers many related teaching ideas. Below are several that are on related topics:
  • Lesson Plan: Fading Away
  • Video: What are Pigments?  
  • Lesson Plan: Introduction to Color
  • Activity: Ingenious Video: What Birds Know about Color that You Don’t