Classifying Organisms with Your Students
By Mary Haugen
Carolina Teaching Consultant
This activity will especially interest your students who like “creepy-crawly” and other types of critters, but you can create a memorable hands-on experience for even the squeamish with live organisms in your classroom. Students learn to care for the organisms and can decipher their unique characteristics while observing them up close. This activity is also an excellent opportunity for students to practice science notebooking.
Organisms are easy to procure from various sources (e.g., borrowing from other classrooms, collecting in students’ backyards, or purchasing through Carolina). Find free care information for our live organisms at www.carolina.com/caresheets. Making students responsible for identification, through field guides or the Internet, enhances the learning experience. Identifying habitat, temperature, and food requirements are other learning opportunities. You may even exercise the option given below for conducting this activity without live organisms!
Housing and caring for live organisms
House and maintain the organisms in clean soap-free containers. An ideal container has a secure lid that doesn’t restrict airflow. Glass or plastic containers are recommended since some insects can chew through cardboard and escape. If organisms are locally collected, utilize their natural habitat substrate or water as a clue or starting point for your habitat creation. Distilled water or untreated tap water is not safe for organisms found in freshwater or marine environments. Make tap water safe with a chemical dechlorinator such as AquaSafe® to remove chlorine and chloramines. Another option is purchasing spring water that comes from a natural source. Note: Check the label to ensure that the water is not from a municipal supply. If the organism originates from a marine environment, carefully read and follow directions when preparing synthetic saltwater. Note: Ensure sufficient time for all minerals to dissolve completely. Place the habitat in a temperature-stable area in your classroom away from heating or cooling vents, windows, or doorways, and never in direct sunlight.
Observing and classifying
Prior to laboratory-exercise day, have students define the following characteristics for each phylum: body symmetry, segmentation, body divisions, degree of encephalization, and number of appendages. This worksheet can help students define each of these characteristics. Provide appropriate materials for students to handle and collect organisms. Depending on the organism’s size, this may include clean cups, pipets, forceps, hand lenses, microscopes, dissecting scopes, or microscope slides. Review proper handling procedures so that students know to treat organisms in a respectful manner.
The Internet is a good source for finding the current biological classification of an organism. The University of Michigan Museum of Zoology Animal Diversity Web (ADW) is a great starting point. Simply enter an organism’s common or scientific name in the search bar and click the “Search” button. Detailed background information about the animal, photos, and classification information will display.
Creating a discussion
From whatever source, have students transfer collected data to 3 × 5" index cards or to this card. Data can include pictures/drawings, the organism’s name, characteristics that determine the organism’s phylum, and the phylum. Students sort the completed cards from simplest to more complex by first taping them to a wall or using magnets to attach them to a chalkboard/dry-erase board. Then students use their researched information and discussions with classmates to help order the cards. Debate is welcome at this point as many scientists do the same thing—agree and disagree on classification of these organisms based on new or emerging scientific research. You can use textbook diagrams as a guide to help students create a simple phylogenetic tree in their science notebooks.
Obtaining organisms from alternative sources
Perhaps live organisms from Carolina or your backyard are not an option for your classroom. There are other alternatives.
- For environmental sciences
If a Berlese funnel is available, have students collect leaf litter samples. While many of the collected organisms may be within the phylum Arthropoda, students can still research where and how each organism fits into the ecological web. Students can compare various locations—wooded natural areas, insecticide-treated lawns, fertilized lawns, and garden or flowerbed soils. From their comparisons, does the variety or number of organisms differ in each place? Are some organisms the same in each location? Do they believe chemical treatments have any effect on what they discovered?
- For anatomical and physiological studies
Students can not only research and discuss organisms, but dissect them and view the differing internal structures that show the progression from simple to complex. For instance, dissecting a fish, frog, and rat to show differences in heart structure is more memorable than simply reading about it in a textbook or viewing an image online.
Insects are also useful in studying rates of cellular respiration. The Carolina™ Volumeter/Respirometer chamber is designed for insects and seeds; the chamber in our Small Animal Basal Metabolism Studies Kit works with organisms weighing over 150 grams. Complete kits are also available for AP® Biology Lab 5 Cell Respiration Kit.