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Some concepts in genetics, such as genetic screens, are complex for students to visualize in a classroom and can be cumbersome to undertake in the laboratory. Typically, very large populations are needed, which can be addressed by using micro-organisms. However, students can struggle with phenotyping microbes. For macroscopic organisms, the number of offspring produced, and the generation time can be challenging. I developed this lesson as a small-scale genetic screen of Fast Plants^®. These plants are amenable to teaching labs as they have simple growth requirements, a short generation time, and produce numerous seeds that can be stored for years. Seeds used for this screen are purchased pre-treated with a DNA damaging agent, removing the need for in-house use of mutagens. Also, students can screen the phenotypes without specialized equipment. The initial lesson begins with an examination of the first generation of plants. Later their offspring are screened for altered phenotypes. Students responded well to having full-grown plants available on the first day of the lab project. This lesson fostered student collaboration, as they worked with class datasets. Differences in growth due to mutagenesis treatment in the first generation were clear to students who had not worked with plants before. Identifying plants with altered phenotypes in the next generation was more of a challenge. This lesson incorporates key concepts such as somatic and germline mutations, the impact of such mutations on phenotype, and the inheritance of mutation alleles, and provides a hands-on way to illustrate these concepts.

Primary Image: Fast Plant^® phenotype differences observed in the M2 generation. This pot contains three full-sibling M2 seedlings from a single M1 parent plant. The seed of their parent plant received 50 Krads of radiation. Plants 1 and 2 are of standard height, while plant 3 is greatly elongated. Image by AL Klocko.

In this lab, students will work with messy data to try to answer the question “How do plants inherit cotyledon color?”

This authentic research experience lesson teaches the core concept of systems and the competencies of quantitative reasoning, communication, and the ability to apply science. The research is student driven, the results are unknown, and the students engage in an iterative process to gather data, collaborating with classmates.  It is designed for first-year biology majors, in a class size of 15-30 students who can work in groups of three.  Students will learn to properly design an experiment, work as teams, analyze data, evaluate conclusions, and communicate findings to others. Additionally, this lesson also incorporates self-reflection and peer assessment when students produce a poster as a summative assessment. Over a five–week period, students will explore how an abiotic factor affects growth, reproduction, and survival of Daphnia.  Students are asked to compare their results to published literature. By the end, students should have a better understanding of science as an ongoing process where results are being updated and furthering the state of knowledge.