The plants around us provide a perfect hands-on biology
classroom for students of all ages. From
planting that first bean in a paper cup to conducting more involved and
complicated high-school biology experiments, studying plants can be an
effective, concrete, fun, and low-cost way for students to explore the living
world.
Kids start learning about photosynthesis from a very young
age. As toddlers begin exploring and
playing outside, their observations help them form ideas about plants and how
they grow. By preschool age, many
students have had the opportunity to plant seeds and water them to see them
sprout. They may find out that plants
will die when we forget to water them or when they don’t get enough sun. As students’ experiences with plants increase,
their perceptions of the way plants grow may change. Often, by the time photosynthesis is formally
introduced in the older grades, students already have some misconceptions about
the process. If we can include
photosynthesis in science lessons from kindergarten on, learning the details of
the process and understanding the chemical reactions involved will be much
easier and more rewarding in middle school and high school.
Since plants are living things, it’s natural for students to
compare the functions of the plants to human functions. Do plants eat, drink, and breathe like
us? How are they different? How are they the same?
One common misconception going into the study of
photosynthesis is that that plants get food from outside sources such as water
and soil, much like humans get their food from outside. All living things need to eat in order to
have enough energy to stay alive. Plants
are the hard-working producers of the world, synthesizing their own food using
energy from the sun. They use carbon
dioxide and water with the sunlight to make their own food internally.
FT Exploring has a very easy to understand introduction to photosynthesis. This resource describes photosynthesis in a
recipe format and includes diagrams that simplify the concepts. It answers the questions of how plants eat,
drink, and breathe, and shows how these functions are different for plants than
for humans. Teachers could use this introduction
for a range of grades, going more in depth with the reactions for older
students and sticking to the more basic facts with younger students. The following diagram is from their site.
In order for a plant to carry out photosynthesis, water must
travel up into the plant from the roots.
This is a fun phenomenon to explore, and would work well for primary or
secondary students. You can introduce
simple chromatography experiments with coffee filters and markers or allow
students to place the stems of white carnations into water dyed with food
coloring. When bands of color travel
out from a marker line or colored water travels to the tips of the carnation
petals, students will gain a visual understanding of how water can make its way
throughout a plant to take part in photosynthesis. Take a look at one of our 2010 blog posts
about fall
lessons to see come neat chromatography ideas.
~Peggy's Corner - September 16, 2011~
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