Five systems will be set up in the classroom to achieve the following 4 objectives:
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Students will construct and maintain a model of a natural habitat and use it to make observations and collect information about live organisms.
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Students will suggest improvements to the model of the natural habitat to make it more realistic and habitable for organisms.
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Students will demonstrate the processes of careful observation and recording for investigating how organisms survive in their habitat.
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4.
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Students will realize that organisms not visible (microbes) in the habitat are essential and make the environment successful.
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Activities One, Two, and Three are formatted to give procedural directions. Each activity can be used as a general classroom example. Another option is to use the procedure to create smaller versions of the habitats for groups of students to assemble, observe, and maintain. Based on the age and ability of the students, the lessons can be adjusted in this manner. The final activity is formatted for individual students. Throughout this unit, the students will keep and maintain science journals to document their observations for each habitat and activity using illustrations and text to share what they are learning. Scientists keep track of their experiments and activities to help them learn as they go and this is an important foundation for the students to become comfortable with and responsible for. Each lesson or activity should be documented in the students' journals as they will serve as an assessment tool.
Although much of the habitat observation will be what the students can see with their eyes, it is important in the unit to acknowledge the role of microorganisms in each activity. The use of a microscope in the classroom would provide tremendous enrichment even if it is borrowed for a day or so. Creating slides to show the microworld in each habitat will make the invisible visible and spark many scientific questions! It is because these microorganisms are in each environment that the environment is successful.
Activity One Setting up the Fish Tank
Materials: 10-- gallon tank/aquarium, gravel, filter, heater, power strip, aquatic plants, plate, bottled bacteria, aquarium test kit for nitrogen cycle, aquarium vacuum, fish food, fish net, bucket, kitchen strainer, 10-15 guppies
Procedure: Rinse out the tank with water only and decide on its location, away from heaters, vents, and direct sunlight. Rinse the gravel before placing it in the tank. After adding the gravel, place any plants or decorations in the bottom. To avoid disturbing the gravel and plants, place an overturned plate in the middle of the tank and pour the water directly onto it. Leave some room at the top to avoid overflow when finishing the setup process. Remove the plate and set up the filter and heater. Add the water to the top now, cover with the tank hood, and plug in all of the equipment. The water needs to sit to reach room temperature and to cycle through the nitrogen cycle. Add some beneficial bacteria and monitor the cycle using the test kit strips. Once the cycle is complete, it is time to add the fish. Adding the fish before the completed cycle will place unnecessary stress on them. Float the bag containing the fish directly in the tank for about 15 minutes so the fish will acclimate to the temperature of the water. After about 5 minutes of floating, add some aquarium water to the bag for the fish to get used to the pH level in the aquarium. Begin feeding the fish on day two but avoid overfeeding give them as much food as they can consume within a minute or two. Regular maintenance generally includes a 20% water change using the aquarium vacuum and a bucket, about every two weeks. Refill the tank with de-chlorinated water.
Activity Two Building a Terrarium
Materials: container (jar, fish bowl, tank, clear bottle with top cut off), pea gravel, clean potting soil, moss, several slow growing plants, science journals
Procedure: Clean the container with soapy water, rinse thoroughly, and dry. Cover the bottom with a layer of pea gravel about an inch deep for drainage. This mimics the bedrock found under our soils and allows excess water to drain from the soil. Next, fill the container to approximately one-third to one-half with moist potting soil. The moisture level of the soil when placed in the terrarium is very important. Pour the soil into a bucket and mix with water until the soil is moist enough to cling together in a ball when pressed into the hand. If water drips when the soil is pressed, it is too wet and more potting soil should be added. After adding the soil, begin placing the plants in an arrangement before actually planting. Be sure to allow for growth and avoid areas where the leaves will touch the sides of the container. After planting, use the moss to cover exposed areas of soil. In addition to plant material, small stones and sticks may add some interest. Attach the container lid or cover with plastic. Place the terrarium away from direct sunlight or the water will evaporate too quickly and the leaves may scorch. Observe the terrarium closely the first few days to ensure the proper moisture level. Droplets of water should appear on the sides and top when there is bright light on the terrarium. If there are no droplets, the terrarium is too dry. If it is too misty, uncover the top for a few hours to allow some evaporation to occur. Prune or remove plants with excessive growth. Occasionally sprinkle the terrarium with water.
Activity Three Ant and Worm Farms
Building the Ant Farm:
Materials: 1 large clear glass jar, 1 smaller jar or can, ½" deep tray for water, shovel, moist soil, cheesecloth, rubber band, dark construction paper, tape, about 100 ants, magnifying glasses, science journals
Procedure: Place the smaller jar or can upside down inside the large jar to encourage the ants to build their tunnels where the students can see them instead of tunneling in the middle. Ants can be collected outside using the shovel to carefully dig enough ants and dirt for the jars. For this unit, I will be ordering ants online to be delivered to the school. Fill the jars with soil 2-3" from the top and add the ants to the jar. Cover the jar with cheesecloth and a rubber band. Place the jar in a tray of water. Although the ants will likely not be able to climb up inside of the jar, they will not cross water. This tray will serve as a moat and they will return to the jar. To encourage the ants to begin working, make a cylinder with the construction paper to slide over the jar. The ants will be more likely to begin tunneling if there is less light it will seem more like underground. Ants like to eat small bread or cracker crumbs, or bread dipped in sugar or with a drop of honey or small bits of apple or other soft fruit and actually like variety in their diet. Feeding them every three days with tiny bits of food and a teaspoon of water twice a week should be sufficient. The farm should not be cluttered with old food or be too wet for them to work.
Building the Worm Farm
Materials: 1 large clear glass jar with lid, 1 smaller jar or can, moist soil, dry oatmeal, hammer and nail, piece of scrap wood, small amount of leaf litter, dark construction paper, worms, tape, magnifying glasses, science journals
Procedure: Place the smaller jar or can upside down in the center of the jar. This will encourage the worms to build their tunnels where the students can see them instead of tunneling in the middle. Put about an inch of moist soil in the jar. Measure about a teaspoon of oatmeal and sprinkle it around the top of the soil. Add another inch of soil and then another teaspoon of oatmeal. Continue layering in this manner, stopping about 2 inches from the top of the jar. Sprinkle some leaf litter around the top of the soil. Place the lid upside down on the scrap of wood and punch several holes into the jar lid with the hammer and nail. Put about 20 worms in the jar and close up the jar with the lid.
Activity Four What's in a Seed?
Materials: dried lima beans two per student, cups of water, hand lens, plastic bag, paper towel, science journals
Procedure: Each student will be given two lima bean seeds, ½ cup of water and a hand lens. Have them place the seeds in the water for twenty-four hours and examine them regularly. Start some seeds independently in case some seeds do not germinate. Have the students make some predictions on what they think will happen to the seeds while they are soaking. After twenty-four hours, have the students determine if the seeds have changed at all after soaking and whether these changes match their predictions. Is there something that could be happening inside the seed? Have each student carefully peel the outer coat from one of the seeds. Then guide them to pull the coatless seed in half with a fingernail. Have them discuss their observations and ask questions to guide them Does any part of the inside of the seed look like a familiar part of a plant? Do you think the seed is alive? Have the students place their seeds, both the whole bean seed and the seed that was split apart, in a plastic bag with a moist paper towel for a week. Have the students record their predictions. Continue observing \ the seeds daily for a week and recording the changes. At the end of the week, have the students share their findings. How did different parts of the seeds change during the week? What happened first? What happened next? Did everyone's seeds change at the same rate or the same order?
Vocabulary: roots, shoots, stem, leaves
If you germinate one bean seed every day for seven days, you will end up with all the stages of germination at one glance.
