🏗️ Engineering: Slow the Erosion

Earth Science Unit 3, Lesson 6 of 6 (Unit Culminating Challenge)

Grade: 2 Duration: 60 minutes Subject: Earth Science, Engineering Design Materials: Baking pan, sand, craft sticks, rocks, leaves, water

NGSS Standard: 2-ESS2-1, K-2-ETS1-1 — Compare multiple solutions designed to slow or prevent wind or water from changing the shape of the land.

🎯 Learning Goals

Apply the Engineering Design Process to a real problem (soil erosion)
Design and test a barrier to slow water erosion
Evaluate results and improve the design

📦 Materials

Baking pan with sand/dirt (same setup as L3)
Craft sticks (popsicle sticks)
Small rocks or pebbles
Leaves (fresh or dried)
Tape (optional)
Cup of water
Pencil/ruler for measuring how far sand moved

📖 Vocabulary

engineering Using science and math to design solutions to real problems

design process The steps engineers follow: Ask, Imagine, Plan, Create, Test, Improve

barrier Something that blocks or slows down movement (like a wall or fence)

erosion control Methods used to stop or slow the movement of soil by water or wind

iteration Repeating a process to make improvements each time

🔬 Background

In Lesson 3, you observed how water moves sand and shapes the land. Now, like a real engineer, you will design a solution to slow that erosion. This is exactly what engineers do in real life! Farmers build terraces (flat step-like shelves on hillsides) to slow water. Civil engineers build retaining walls with rocks or concrete to hold soil in place. Environmentalists plant deep-rooted grasses and trees so roots hold the soil together. All of these are erosion control solutions.

Engineers follow a design process: Ask (what is the problem?), Imagine (what could work?), Plan (draw your design), Create (build it), Test (pour the water!), and Improve (what would make it better?). The "Improve" step is the most important. Engineers rarely get it perfect the first time. Each test teaches you something new that helps you improve your next design.

The materials we will use today (craft sticks, rocks, and leaves) are simplified models of real engineering materials. Craft sticks are like retaining walls or wooden fences. Rocks are like riprap (the large boulders placed along riverbanks and hillsides). Leaves are like planted vegetation. Real engineers think about cost, durability, and environmental impact when choosing materials. You will think about what works best!

🧪 Activity: Erosion Barrier Challenge

Step 1: Rebuild the sand hill from L3 in the baking pan (use the same slope).

Step 2: First, do a control test: pour one cup of water over the unprotected hill. Mark or measure how far sand traveled. This is your "before engineering" measurement.

Step 3: Rebuild the hill again.

Step 4: Design Phase: Look at your materials (craft sticks, rocks, leaves). On paper, sketch your barrier design BEFORE building. Think: where will you put it? How will you arrange the materials?

Step 5: Build your barrier on the hill using your chosen materials.

Step 6: Test Phase: Slowly pour one cup of water from the top. Measure how far sand moved this time.

Step 7: Compare: did your barrier slow the erosion? By how much?

Step 8: Improve Phase: What did not work well? Redesign and rebuild your barrier, making at least one change. Test again.

Step 9: Final comparison: which design worked best and why?

💬 Discussion Questions

Q1: What worked best: craft sticks, rocks, or leaves? Why do you think that material worked better?

Hint: Rocks usually work best because they are heavy and do not move. Craft sticks work if they are pressed into the sand firmly. They act like a wall. Leaves alone tend to wash away because they are light. In real life, a combination (like rocks plus plants) works best. The rocks stop the water and the plant roots hold the soil below.

Q2: What would you try if you had one more test? What improvement would you make?

Hint: Encourage creative thinking. Good answers: packing rocks more tightly, making the barrier taller, using more layers, making the slope less steep, adding multiple rows. All of these are things real engineers try. There is no single right answer. This is engineering thinking!

✏️ Student Worksheet

Engineering: Slow the Erosion - Student Worksheet

Name: _________________________ Date: _____________

1. Design sketch

Draw your barrier design BEFORE building it. Label the materials you will use.

2. Data table

Test	How far did sand move?
Test 1 (no barrier)	Sand moved ___________ cm
Test 2 (my barrier)	Sand moved ___________ cm
Test 3 (improved barrier)	Sand moved ___________ cm

3. Reflection

What worked best?

___________________________________________________________________________

What would I change next time?

___________________________________________________________________________

4. Real-world connection

Name one way real engineers slow erosion in real life:

___________________________________________________________________________

👩‍🏫 Parent/Teacher Notes

Culminating activity: This is the unit culminating activity. It brings together erosion (L3), landforms (L1), and engineering thinking.
Material substitutions: If craft sticks are not available, use pencils, straws, or twigs from outside. Anything stick-like works.
Measurement: The measurement does not need to be precise. Approximate comparisons ("sand moved to the edge" vs. "sand only moved 2 inches") are totally fine.
Real-world discussion: Ask: "What do real engineers use to stop erosion?" Good real-world answers: retaining walls, sandbags, riprap (large rocks), planted vegetation, silt fences, terraced hillsides.
Additional standards: This lesson connects to engineering standards K-2-ETS1-1 (defining a simple problem that can be solved through the development of a new or improved object or tool) and K-2-ETS1-3 (analyzing data from tests of two objects to compare the strengths and weaknesses of how each performs).

✂️ PARENT ANSWER KEY

Worksheet Answers

Design sketch: Accept any labeled sketch that shows materials placed on or around the sand hill. Look for thoughtful placement (barriers across the path of water flow, not random placement).
Data table: Answers will vary. The key check: Test 2 and Test 3 measurements should generally be less than Test 1 (the barrier should slow the erosion). If not, discuss why and what could be improved.
Reflection: Accept any thoughtful response. Good answers identify which material or arrangement worked and explain why (heavier materials stayed in place, multiple rows slowed water more, etc.).
Real-world connection: Accept any of: retaining walls, planting trees/grass, sandbags, riprap (large rocks along riverbanks), terracing hillsides, silt fences. Any reasonable erosion control method is correct.