1. Science Buddies – “Rain Garden Science Experiment”

A super approachable, hands-on activity where kids build a miniature rain garden, simulate runoff, and observe how well it soaks up water. It’s STEM-aligned and perfect for fairs or casual demonstrations.
YouTube

2. MnSTEP via Teach the Earth – “Exploring Run-Off and Infiltration in the Classroom”

For younger learners (K-2), students use three simple cups (with soil and different materials like sponges or tin foil) to see how much water filters through. It’s group-based, inquiry-driven, and ideal for sparking curiosity.
SERC

3. Clermont SWCD – Rain Garden School Activity Guide

This guide includes six adjustable lessons, with versions tailored for elementary students. Activities like “Nowhere to Run” and “Capture, Store and Release” are student-friendly, interactive, and easy to set up.
clermontswcd.org

4. KidsGardening – Rain Gardens Lesson Plans

Perfect for elementary classrooms—students measure, draw, and build rain garden models with watering cans, learning how these gardens slow runoff and filter water naturally.
KidsGardening

5. Great Lakes / Alliance for the Great Lakes – Mapping Infiltration Activity

A simple at-home or classroom activity where students explore local surfaces and predict how water moves—solid for getting kids thinking about real-world terrain and how water soaks in.
Alliance for the Great Lakes

6. PBS LearningMedia – Land Cover, Runoff & Infiltration Investigation

Students investigate how different surfaces influence water runoff versus absorption—great for comparison experiments like your tray idea.
PBS LearningMedia

7. UNL Water / Project WET – Stormwater Education for Kids

Project WET offers tons of hands-on games and lesson ideas to teach youth about water cycles, pollution, and green infrastructure like rain gardens.
water.unl.edu

8. Arizona Project WET – Stormwater Runoff Demo Video

A quick visual guide (teacher demonstration style) showing how capturing rainwater helps reduce runoff—great for visual learners or as a quick fair demo.
YouTube