Description

For students to have a better understanding of aspects of reproduction and see how they relate to each other, we have designed a unique six-week project.  The topics covered during the six weeks are all interconnected and will therefore allow the students to obtain a strong conceptual basis of all types of reproduction.  The project connects many topics that might normally be taught at different times over the course of the year or in a disconnected fashion.  Our project begins by discussing the different types of reproduction beginning with asexual reproduction and moving into sexual reproduction, with an emphasis on human reproduction.  The discussions begin at a molecular level and move from there to consider the broader picture.  The project pays attention to errors in sperm and egg production, the genetic technology used in this field, and the ethics surrounding it.  The project will include a mixture of inquiry-based labs, research, stimulating lectures, debates, and culminates with the students playing the role of a genetic counselor.

Driving Question

            The question our students will answer over the course of the project is: How do different organisms reproduce and what happens when something goes wrong?

Overall Goals

            We anticipate that this project experience will create an increased sense of interest and accountability in the classroom, a broader knowledge base about reproduction, and higher TAKS scores. We also hope that these project-based teaching methods will serve as a model for other teachers in our school and community.

Project Objectives

Students will be able to:

• Identify the spore, sperm, and egg of a moss plant
• Relate the structures of the moss plant to their functions for reproduction
• Discuss alternation of generations in terms of diploid and haploid life forms, sexual and asexual reproduction, and meiosis and mitosis
• Diagram the reproductive life cycle for moss
• Discuss the evolution of plants from water to land

• Prepare a slide mount of sea urchin sperm and egg
• Observe fertilization, cleavage, and gastrulation in the sea urchin embryo
• Explain how fertilization occurs in sexual organisms
• Consider the consequences of polyspermy

• Pair homologous chromosomes
• Interpret a karyotype
• Use a karyotype to make a medical diagnosis
• Describe representative chromosomal disorders
• Explain the importance of pollen for plant reproduction and diversity
• Explain asexual reproduction
• Understand case studies and relate them to their project
• Identify and understand key vocabulary terms
• Connect the case studies to real world applications

Rationale

Despite a national move towards hands-on science, U.S. science scores remain low. Eighty percent of U.S. twelfth graders are still not meeting the National Governing Board's definition of proficiency in science (NCES, 2000). Based on detailed analysis of TIMSS data, William H. Schmidt, attributes this low performance to a disconnected curriculum containing too many topics that are not covered in depth.  This problem has yet to be solved.

One topic that is often underrepresented in the classroom is reproduction.  We have created a project that deeply covers all aspects of reproduction while reinforcing key themes in biology namely evolution, genetics, and structure/function relationship. By utilizing a high interest topic, sex, students will grapple with key biological concepts that are often viewed as dry and unrelated to everyday experience.  The goal will be to foster connections between biological concepts and real world applications. 

This project takes what might seem like a simple topic and has the students deeply explore it over six weeks.  By the end of the six weeks, the students will become experts who must demonstrate their knowledge by playing the role of a genetic counselor.  This expertise proves that the students have thoroughly explored reproduction and connected it to real world applications.

Background Information

            DNA (deoxyribonucleic acid) is the genetic material in all living organisms.  It contains information in segments called genes and is packaged in chromosomes.  Humans typically have 23 pairs of chromosomes (46 total) receiving one set of 23 from their mother and another set of 23 from their father.  Genes are transcribed into RNA messages which are read by ribosomes that produce proteins.  Proteins are polymers made up of amino acids.

Organisms produce either sexually, asexually, or through a combination of the two methods.  In asexual reproduction, the organism literally makes a copy of itself with identical genetic material and that is the offspring.  In sexual reproduction, fertilization is required.  Cells in the ovaries and testes undergo meiosis resulting in egg and sperm containing half the number of original chromosomes.  The egg and sperm then join in fertilization to create a zygote that contains 2 sets of chromosomes, 46 total.  This single cell divides by mitosis to form a multicellular organism with differentiated tissues.

Plants undergo a unique type of reproduction in which the generations alternate between sexual and asexual reproduction.

Unfortunately, the creation of sperm and egg does not always go perfectly.  If there is an error in meiosis, it is possible that a sperm or egg could end up with extra of missing chromosomes.  These problems are known as aneuploidies (a single extra or missing chromosome) or polyploidies (an entire extra set of chromosomes).  It is possible to detect these problems using certain types of genetic technology such as karyotyping, amniocentesis, and chorionic villi sampling.  These technologies allow for a picture of a set of human chromosomes to be created.  By looking at the picture, you can determine if there are any extra or missing chromosomes and if all of the chromosomes are in tact.  Genetic counselors are professionals who specialize in genetic disorders and how they occur.  They share this information with patients who are then able to make decisions about starting a family, a particular pregnancy, the care of a child, etc.

Standards Addressed

TEKS:

(1) Scientific processes.  The students, for at least 40% of instructional time, conducts field and laboratory investigations using safe, environmentally appropriate, and ethical practices.  The student is expected to:

(A)  demonstrate safe practices during field and laboratory investigations; and

(2)  Scientific processes. The student uses scientific methods during field and laboratory investigations. The student is expected to:

(D) communicate valid conclusions.

(3)  Scientific processes. The student uses critical thinking and scientific problem solving to make informed decisions. The student is expected to:

(A) analyze, review, and critique scientific explanations, including hypotheses and theories, as to their strengths and weaknesses using scientific evidence and information.

(6) Science concepts.  The student knows the structures and functions of nucleic acids in the mechanisms of genetics.  The student is expected to:

(E) compare the processes of mitosis and meiosis and their significance to sexual and asexual reproduction

(F)  identify and analyze karyotypes.

(13)  Science concepts. The student knows the significance of plants in the environment. The student is expected to:

(A)  evaluate the significance of structural and physiological adaptations of plants to their environments; and

(B)  survey and identify methods of reproduction, growth, and development of various types of plants.

National Technology Standards:

1. Basic operations and concepts

á      Students demonstrate a sound understanding of the nature and operation of technology systems.

á      Students are proficient in the use of technology.

2. Social, ethical, and human issues

á      Students understand the ethical, cultural, and societal issues related to technology.

á      Students practice responsible use of technology systems, information, and software.

á      Students develop positive attitudes toward technology uses that support lifelong learning, collaboration, personal pursuits, and productivity.

3. Technology productivity tools

á      Students use technology tools to enhance learning, increase productivity, and promote creativity.

á      Students use productivity tools to collaborate in constructing technology-enhanced models, prepare publications, and produce other creative works.

5. Technology research tools

á      Students use technology to locate, evaluate, and collect information from a variety of sources.

National Science Standards

á      Science as inquiry standards

o      Abilities necessary to do scientific inquiry

o      Understanding about scientific inquiry

á      Life science standards

o      The cell

o      Molecular basis of heredity

o      Biological evolution

o      Interdependence of organisms

o      Behavior of organisms

á      Science and technology standards

o      Understanding about science and technology

Description of Formative and Summative Assessments

A rubric has been created for the entire unit and acts as formative assessment.  This rubric includes Vee maps for investigations, homework assignments, a research paper, debate research and presentation, and a final presentation.  The Vee map is a tool to help the guide the students' thinking and learning during the investigations.  It includes a focus question that guides the investigation, a concept map over the theories and science behind the investigation, a word list over the science concepts, data analysis, and a conclusion.   The homework, research paper, and debate will act as benchmarks to ensure that the students are on task and understanding the big concepts of the unit.

A separate rubric has been created for the final presentation so that the students know exactly what is expected of them.  For the final presentations, the groups will each assume the role of a genetic counselor during a simulated genetic counseling session.  The teacher will play the "patient."  The students will have to explain biological concepts at a molecular level, take a family history, diagnose the patient, and offer options.  After the session the group will write an official letter to the "patient's doctor" informing them of what went on during the genetic counseling session.  This rubric will allow the teacher to grade each group fairly and efficiently.

A list of assessment techniques has been compiled for use throughout the project.