A Recipe for Soil
Lesson Objective
Students make soil using local materials and compare plant growth in natural and student-made soil.
Background Information for Teacher
Student Prior Knowledge
Denim soil-making bag
Dead leaves and other plant material
Hammer or mortar and pestle
2 small cups or flower pots
Fast growing seeds (radish, grass, lettuce)
Latex gloves or plastic sandwich bags for students to wear on hands
Step-by-Step Guided Lesson
Step 1: Start Video
(Tips: Interact with the video by pausing, to ask questions or discuss information viewed with student.)
Step 2: Teach Lesson
Soil is the material that constitutes the outermost layer covering practically all of the Earth's land surface. Soil is made of air, water,
humus (decayed organic material) and rock particles. Soil is formed by the slow process of weathering (the breaking down of rock),
erosion (the moving and deposition of weathered rock material), and the combining of those rock particles with air, water and organic
material. It can take from 100 to 600 years or more for nature to make one inch of topsoil.
Review with the student the "recipe" for soil: 25% air, 25% water, 45% rock particles, 5% organic material.
Explain to the student that they are going to make soil by replicating natural processes. They will gather organic material, "weather
and erode" rock material, and mix it with air and water to grow a plant.
Ask the students to gather
1. dead leaves
2. small twigs
3. flower petals
4. other small plant material
5. pebbles
6. sand
More pebbles and sand than organics are needed because soils contain more rock parts than they do organics.
Place all materials in a small bag made of denim or other heavy material (or use mortar and pestle to grind materials). Pound mixture
with a hammer until the rocks are pulverized.
Remove from the bag, place in planting pot, and add water (the act of pouring the materials into the pot will add air to the mixture).
Repeat this process until you have enough soil to fill a small cup or flower pot 3/4 full.
Plant 10 seeds in their soil and 10 more seeds in a pot containing natural soil (not potting soil). Then observe and compare the
growth. This will take a week or more. Have the student note when the seeds begin coming up out of the ground. Have them
measure the seedlings as they grow. They should also record how many of the ten seeds came up on each of the pots.
Relate the components of soil to the growth of plants in soil. Remind the student of the following:
a.Water is necessary to carry nutrients into the roots and up the stem. It is also necessary for the plants to grow.
b.Air is necessary to allow the roots to "breathe". Also, air spaces in the soil allow a place for water to enter the soil.
c.Organic matter, plant and animal parts, help hold the water in the soil. They also provide nutrients.
d.Rocks and minerals provide nutrients to the plants and structural support to the roots.
Ask the student how they could provide mineral nutrients for plants to grow without soil. List their responses. Responses might
include: grow plants in wet towels, grow plants in wet gravel, grow plants in water.
At the end of the week, help the student write a lab report. Their lab report should contain:
a. A clear statement of the question they were trying to answer. (In this case, it was something like, "Will plants grow
better in the soil I made or in natural soil.)
b. A description of their materials and set up.
c. A record of the data they collected (when the plants came up, how many came up, how much they grew). The could
be recorded in a table or in graph form.
d. A conclusion that states what they learned from the experiment. Did it answer the question they asked? If so, what
was the answer?
Step 3: Complete the worksheet attached below.
Activity Worksheet for in depth learning
Step 4: Review. Start the next lesson with the game or activity attached below for review so the student can demonstrate
understanding of this lesson before moving forward.
Soildoku (offline) worksheet