Lesson Plan (Grades 3-5): Edible Water Bottles - Biodegradable Polymer Science

Lesson Title: Edible Water Bottles: Biodegradable Polymer Science

Grade Level: Grades 3–5

Subject Area: Chemistry / Environmental Science

Overview In this hands-on lesson, students explore how a simple kitchen chemistry reaction—mixing sodium alginate with calcium chloride—can produce edible, biodegradable “water bubbles” that hold liquid like tiny water bottles. Through guided experiments, they investigate polymer cross-linking, measure and compare bubble sizes, and test membrane strength. Finally, students examine real-world applications and environmental implications of edible packaging, fostering curiosity about sustainable materials.

Objectives and Standards

Learning Objectives

1. Explain how sodium alginate and calcium ions react to form a gel membrane (polymer cross-linking).
2. Measure and compare bubble diameters created with different alginate concentrations.
3. Test and record the mechanical strength and stability of edible spheres under gentle pressure.
4. Discuss environmental benefits and challenges of edible water packaging as a plastic alternative.

Standards Alignment

• NGSS
  • 5-PS1-4: Conduct an investigation to determine whether mixing two or more substances results in new substances.
  • 3-5-ETS1-2: Generate and compare multiple solutions to a problem based on how well they meet criteria (edible, biodegradable packaging).
• CCSS for ELA
  • W.3–5.2: Write informative/explanatory texts to examine a topic and convey ideas clearly.
  • SL.3–5.4: Report on a topic or text, telling a story with appropriate facts and descriptive details.