Table 1. Performance expectations suggested by the Next Generation Science Standards (NGSS Lead States, 2013) that require (in bold) or allow (not bold) exploring sexual selection and suggestions to explore these expectations in the classroom.
School levelExpectationExpectation descriptionExamples of resources that can be used in the classroomSuggestions to explore the Nature of Science expectations
Elementary schools3-LS4-2Use evidence to construct an explanation for how the variations in characteristics among individuals of the same species may provide advantages in surviving, finding mates, and reproducing.Explore this expectation with the activities presented in this paper.

Explore the Birds-of-Paradise Project website for additional information on individual traits that may provide advantages in reproduction.
Scientific investigations use a variety of methods, tools, and techniques to produce and revise scientific knowledge.

Explore the activities proposed in this paper and in Lawson (2003) as examples of models similar (although simpler) to those used by researchers to simulate and study evolution, and contrast this research methodology with those presented in the Birds-of-Paradise Project, Human Endeavor, Methods & Technology.
Elementary schools4-LS1-1Construct an argument that plants and animals have internal and external structures that function to support survival, growth, behavior, and reproduction.Birds-of-paradise have feathers with distinct functions: flying, protection from the environment, and attracting mates. Discuss with your students what could be the function of these distinct feathers using the resources available on the Birds-of-Paradise Project website.Scientific findings are based on the recognition of patterns.

Discuss with your students how patterns of feather coloration, size, position, and structure may help scientists to construct hypotheses regarding the function and origin of a particular feather.
Elementary schools4-LS1-2Use a model to describe that animals receive different types of information through their senses, process the information in their brain, and respond to the information in different ways.Use the variety of traits and displays of birds-of-paradise to explore this expectation. Resources are available at the Birds-of-Paradise Project website.Men and women from all cultures and backgrounds choose careers as scientists…
Most scientists and engineers work in teams.
Creativity and imagination are important to science.


Use information about how scientists from distinct cultures and backgrounds work in teams and use their imaginations to gather information about birds-of-paradise, available on the Birds-of-Paradise Project website (Human Endeavor). Use also Lesson 1 from Fee and Alfano (2013).
Middle schoolMS-LS1-4Use argument based on empirical evidence and scientific reasoning to support an explanation for how characteristic animal behaviors and specialized plant structures affect the probability of successful reproduction of animals and plants, respectively.Start exploring sexual selection by presenting students with species having distinct degrees of sexual dimorphism and providing information about their ecology, sex ratios, and mating systems. With this, motivate your students to use evidence to construct hypotheses and scientific arguments. Use the activities described in this paper to test your student's hypothesis.Science depends on evaluating proposed explanations.

Use the activities proposed in this paper as evolution simulators to gather empirical evidence to evaluate students’ hypotheses to explain patterns of sexual dimorphism. Highlight this evaluation process.
Middle schoolMS-LS4-4Construct an evidence-based explanation that describes how genetic variations of traits in a population increase some individuals’ probability of surviving and reproducing in a specific environment.Explore this expectation with the mate choice activity presented in this paper. Perform the activity under distinct sex ratios and/or mating systems, allowing students to explore the evolutionary outcomes under these social environments. Further, use the example of lizards, Uta stansburiana, to highlight the importance of social context in evolutionary outcomes (Sinervo & Lively, 2006).Scientific knowledge is constrained by human capacity, technology, and materials.

Discuss with students the similarities and differences between their simulations of evolution based on this paper and evolution simulators used by researchers to test their hypotheses and predictions. Discuss how the advance of computational resources affected the use of evolution simulators to test hypotheses.
Middle schoolMS-LS4-6Use mathematical representations to support explanations of how natural selection may lead to increases and decreases of specific traits in populations over time.Use the simulation proposed in Lawson (2003) to explore this expectation. Ask students to identify natural selection and sexual selection strengths, and to predict outcomes for scenarios with distinct relative strengths.Scientific explanations are subjected to revision and improvement in the light of new evidence.
Science depends on evaluating proposed explanations.


Explore research projects that test weather giraffes’ neck size evolved through natural or sexual selection (Simmons & Altwegg, 2010).
High schoolHS-LS4-2Construct an evidence-based explanation that the process of evolution primarily results from four factors: (1) the potential for a species to increase in number, (2) the heritable genetic variation of individuals in a species due to mutation and sexual reproduction, (3) competition for limited resources, and (4) the proliferation of those organisms that are better able to survive and reproduce in the environment.Explore this expectation with the activities presented in Bouwma-Gearhart and Bouwama (2015) or with those presented in this paper. To contrast the effects of natural and sexual selection, you may compare the results obtained with the activities described in this paper with those described in Campos and Sá-Pinto (2013).Science distinguishes itself from other ways of knowing through the use of empirical standards, logic arguments, and skeptical review.

Explore this expectation with the activities presented in Bouwma-Gearhart and Bouwama (2015).
High schoolHS-LS4-3Apply concepts of statistics and probability to support explanations that the populations of organisms with an advantageous heritable trait tend to increase in proportion to organisms lacking this trait.Explore this expectation with the mate choice activity presented in this paper. Perform the activity under distinct sex ratios and/or mating systems, and for each scenario, ask students to estimate the probability of each male to have offspring in the next generation, taking into account his traits. Discuss how this information helps you to predict the evolutionary outcomes under each scenario.Scientific investigations use diverse methods and do not always use the same set of procedures to obtain data.

Ask your students to make a list of the most common bird species around them and to gather data to test if sexual dimorphism tends to be more frequent in polygamous than monogamous species. Ask them to contrast their results with those obtained in the simulation.
High schoolHS-LS2-8Evaluate the evidence for the role of group behavior on individual's and species’ chances to survive and reproduce.Use the two distinct, colorful male types of the mate choice activity in this paper to discuss how the frequency of female preferences affects the male's chances to reproduce.New technologies advance scientific knowledge.

Discuss with your students how the evolution of genetic technologies allowed scientists to study female cryptic choice that occurs after copulation or spawning.