Lesson Title: What are decomposers?
Teacher: Mark Diehl
School: Walnut Park
Grade: Four
Date: Oct. 21, 2010
Subject: Science
Time: 10:30am to 11:30am
Rationale: Students investigate and examine decomposers at work by looking at the
structure of decomposers through the use of a microscope.
Prescribed Learning Outcome (from standards):
Processes and Skills of Science
Students will be expected to:


use their senses to interpret observations
use date from investigations to recognize patterns and relationships and reach
conclusions
Life Science: Habitats and Communities
It is expected that students will:

determine how personal choices and actions have environmental consequences
Materials Required:
 misc food waste items
 clear containers for food items
 magnifying glasses
 bread in a bag
 decomposing bread observation sheet
 felt markers
 Compost work sheet
 Microscopes (4)
Assessment:
 Student work sheet
o checking for comprehension and student understanding of composts and
decomposition
 Observation
Procedure:
Activity/Materials
Review
3 min
Anticipatory Set
Teacher Actions
- review with students producers and consumers
- ask students what they think decomposers are
- create decomposer web chart on the board and have
1
5 min
Input (I do)
5 min
Guided Practice
8 min
Individual Work
8 min
Closure
3 min
students brainstorm things that happen to waste
- could be smell, appearance, etc.
- ask students what happens to leaves and bark that to the
ground?
- what happens to plant and animals that die in the forest?
- are dead organisms recycled in some way?
- what do you think causes living things to decay?
- write students responses on the board
- inform students that you have place some bread on the
back counter in a sealed bag and that there is a sheet for
them to write down observations that they see (the bread
changing from different decomposition stages) using the
magnifying glass (example: I see that the bread is growing
mould)
- they should write their name and date of their observation
in the spaces provide
- tell the students that we will be looking at some items for
evidence of decomposition
- have students write down things that they notice on the
items using the magnifying glasses
- have students return to their seats and discuss what they
saw with a partner
- have students share what they saw
-explain to the students that during the next activity you
will be calling groups up to look at fungi through a
microscope
- give the work sheet to students and explain the
instructions
- students who finish early can do the last question
- tell the students that when they are finished to hand it in
to you
- as students are working on their worksheet, invite groups
of four up to examine decomposers under the microscope
- as students look at the fungi at different magnify, ask
students questions about what they see such as: what does
the it look like (shape, texture, color, etc)? Is this a better
way to look at decomposers rather than the magnifying
glass? Why?
- review with students what decomposers are with some
examples
- ask students to share what they saw under the microscope
- tell students that next class we will look at food chains
Vocabulary
2
Decomposers: organisms such as fungi and bacteria that break down animal and
plant matter into nutrients
Fungi: spore producing organisms without chlorophyll, such as mushrooms,
mould, and yeast, which live by absorbing plant and animal matter. They are
decomposers.
3