Are you teaching the water cycle or studying soil in your classroom or homeschool? Measuring infiltration rates in different types of soils is a hands-on activity that helps students explore how water interacts with the ground. This soil infiltration activity also ties in perfectly with studies of porosity and permeability. This engaging experiment works as a stand-alone lesson or as part of a broader unit on soil science or the water cycle.
Before we dive in: The activity from this post comes from my complete Water Cycle Unit. If you’re an educator planning to teach infiltration and the water cycle, you’ll find printable directions, worksheets, and much more in the Water Cycle Unit (plus you’ll support my blog with your purchase! ❤️)
Materials
Gather the following materials to complete this activity:
- Short tube or pipe with openings on both ends, something sturdy works best:
- A short PVC pipe
- Or potentially a sturdy can opened on both ends (file down any sharp edges before use)
- Ruler
- Permanent marker
- Hammer or rubber mallet
- Water
- Stopwatch
- Student worksheets & printable directions (available in my Water Cycle Unit!)
Measuring Soil Infiltration: Step-by-Step Directions
The basic idea of this soil infiltration activity is that you will hammer a tube shallowly into the soil, then pour water in, and observe the water level drop as the water seeps into the ground. Assist your students as they work through the following steps.
Pre-Lab
In this lab, students will compare the infiltration rate in at least three different locations with different types of soil. For example, they could compare a sandy soil, a clay soil, and a soil rich in organic matter.
Before starting the lab activity, ask your students to observe and handle the three different soils. Students should write a description of each soil’s observable properties (color, texture, moisture, particle size). Then, students should predict which soils will have the highest and lowest infiltration rates. Students should explain their reasoning for their predictions.
Part 1: Set Up Your Infiltrometer
First, you and your students will need to set up your “infiltrometer” (tube for measuring infiltration rates).
- Use a ruler and permanent marker to make measurement markings up the inside of the tube, starting from one end.
- Hammer the infiltrometer (tube) into the soil – the goal is to create a seal with the soil so that water won’t leak out under the tube’s rim. (An adult should complete this step for younger students.)
Part 2: Measure Infiltration
Once you’ve set up the infiltrometer, you are ready to continue with the soil infiltration activity and collect your measurements.
- Pour water into the infiltrometer.
- Note the starting height of the water and start the stopwatch.
- Watch the water level in the infiltrometer lower as the water seeps into the soil.
- Repeatedly record the water level over time on the student worksheet.
- Repeat in different soils – compare a sandy soil, flowerbeds, mulch, gravel, sand, compost, etc.
Post-Lab
For an extra math challenge: Calculate the infiltration rate for each of the soils:
You may also wish to ask your students to reflect on their predictions. Were their predictions correct? Which soil had the highest infiltration rate? The lowest? What might cause this?
What’s Next?
Once you’ve measured infiltration, why not measure other water cycle processes? Be sure to check out my blog post explaining how to measure evaporation and my post on making a DIY rain gauge to measure precipitation with your students!
Materials for Teaching Infiltration and the Water Cycle
Save time preparing for this activity! My Water Cycle Unit includes printable directions and worksheets for this activity and two other water cycle activities. Plus flashcards, diagrams, and more. Check it out:
Explore more lessons from Wild Earth Lab:
If you enjoyed this post, I know you will love trying my other printable science and nature units in your classroom too!
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