Aztec Floating Gardens

Vanessa Villalobos Oscar Mayer Elementary
2250 N. Clifton
Chicago IL 60614
(312) 534-5535


This lesson was created for students of all ages at the elementary level
grades K-8. Students will be participating in a series of short experiments
involving plants in order to discover ways to create a hydroponic garden.
Aztec history will be explored to gain student interest and to set up the
background for the analysis and creation of the "Floating Gardens".

Background Information:

The basis of this project is phenomena derived from Aztec history.
The Aztec civilization thrived for three centuries and successfully grew a
multitude of produce including pumpkin, squash, and corn. The amazing aspect is
that their crops were underwater due to the fact that where they were located,
Tenochtitlan (now known as Mexico City), was primarily wet, marshy land. In
order to survive, the Aztecs had to create ingenious ways of producing crops in
underwater conditions. The students, like the Aztecs, will be faced with the
problem of recreating an underwater garden in the classroom.

Materials Needed:

-celery stalks (8 to 10 depending on class or group size)
-red or blue food coloring
-clear plastic cups
-1 lb bag of sand
-1 lb bag of potting soil
-seeds of various plants i.e. peas, Mexican sunflowers, beans, etc.
-ziploc baggies
-paper towels
-large, clear plastic containers (garden itself)
-10 carrot tops (sliced from carrots)
-10 sponges (artificial or real, although real will work best)
-white carnations (optional)
-steel or plastic mesh
-large square or rectangular tupperware containers

Time Constraints:

This unit, depending on class setup, will require one to six weeks.


Mini-experiment #1:

This first "mini-experiment" will introduce the concept of how plants
acquire nutrients from the stem upward.

1. Add 8-10 drops of red or blue food coloring to water in a clear cup.
2. Place a celery stalk or white carnation inside the cup.

Within 20 minutes, students will observe that the dyed water has been
transported upward within the stem and has been deposited at the leaf tips. If
possible, have the students observe a cross-section of the celery (or flower)
under a microscope and label all parts. The next day, the changes will be even
more dramatic, the leaves having a vibrant, dyed color.

Mini-experiment #2:

This mini-experiment will dispel a common idea among students; that only
the method of growing plants is with black soil and seeds.

1. In a small circular pan (the black bottoms of 2 liter bottles will also
suffice) add 2 inches of sand.
2. Cut the tops off of several carrots and place them in the pan with sand.
3. Add a small amount of water to the pan, enough to make the sand damp.

Within a few days, the students will observe the carrots beginning to
sprout. The carrot tops contain the necessary elements to grow into another
carrot plant and can be transported at another time.

Mini-experiment #3:

This experiment will build upon the previous activities' concepts and
continue to establish that plants can grow in various environments.

1. Soak a variety of beans in a pot for one evening (if this step is not
completed, the seedlings will sprout, but will take a longer time).
2. Fold a paper towel into fourths and add enough water to dampen the
towel throughout. Place the towel inside a ziploc baggie.
3. Place 8-10 beans inside the baggie on top of the folded towel.
4. Tape the baggies to the window.

In a few days, the students will observe many changes and should take
detailed notes. Discuss the idea that inside each seedling lies "a baby plant"
waiting to grow.

Mini-experiment #4:

The students should now be knowledgeable and ready to create their floating
gardens. Working in groups, the students should make a list of materials needed
for their gardens and then set out to obtain those materials on their own.
However, depending on the age level, this may not be possible. In any case, the
students may need a variety of materials with which to begin. Soil, sand,
plastic containers, seeds, and plastic or wire mesh are the staples of this
experiment. Allow the students to work with their groups to discuss and draw
up plans for their gardens using previous experience and research.

1. Take the large, plastic tupperware containers (or similar containers), and
have the students fill them almost completely with water.
2. Using different materials, the students should now construct their floating
gardens based on the group's plans, ideas, and drawings.

It will be interesting to see the different combinations the students have
created. Some will create gardens with sand bottoms, soil bottoms, or a mix of
both. Other groups may make multi-level gardens with irrigation systems.

Performance Assessment:

Once the students have completed their gardens, they should present
them to the class. Students are to explain how they built their gardens and why
they think their gardens will enable plants to grow. Questions can then be
presented to the groups to guide discussions and provide constructive criticism.
Each student should then keep detailed notes of all activities and changes that
occur within the gardens.

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