Natural selection

The Natural selection SAILS inquiry and assessment unit focuses on natural selection and the Darwinian theory of evolution, which is part of the biology curriculum at upper second level in most European countries. The topic is addressed in a structured, hands-on activity, during which students simulate a gene pool and the random selection of alleles. They assemble model organisms, called Legorgs, out of Lego® bricks, and measure their fitness. They use this physical simulation to grasp the underpinning concepts of adaptation by natural selection.

The skills developed in this unit include planning investigations, forming coherent arguments and working collaboratively. Skills in scientific reasoning, such as collecting data, drawing conclusions are enhanced and students' scientific literacy is enriched through comparisons between the physical simulation and the real world. This activity is recommended for implementation at upper second level, where students have sufficient mathematical knowledge to numerically analyse a large quantity of data, and have conceptual understanding of the biology involved. The assessment methods described in the unit include teacher observation, use of student artefacts and classroom dialogue.

This unit was trialled by teachers in Poland, Hungary, Denmark and Sweden – producing five case studies. In all cases, the teaching approach was guided inquiry, although teachers also allowed open inquiry where feasible. Students were aged 14-19 years, with those in Poland and Sweden at lower second level. Skills assessed included planning investigations, working collaboratively, scientific reasoning and scientific literacy.

Unit booklet

Key content / concepts

Visualising evolution: gaining a deeper understanding of the biology and random nature involved
Natural selection
Genetic drift
Fitness

Level

Lower
Upper

Inquiry skills and competencies assessed

Planning investigations
Forming coherent arguments
Working collaboratively
Scientific reasoning
Scientific literacy

Assessment methods

Classroom dialogue
Teacher observation
Worksheets
Student devised materials
Other assessment items

The Natural selection SAILS unit details a hands-on exercise on natural selection, designed for students aged 15-18 years, in which they investigate multiple genes in LEGO animals (Legorgs). The teaching and learning activities described in this unit were developed by Christensen-Dalsgaard and Kanneworf (published in Evolution: Education and Outreach, in 2009) and adapted for use in the SAILS project. Materials related to the unit activities, including instructional videos, are available from http://www.jcd.biology.sdu.dk/

The three key concepts addressed in this activity are: 1) Natural selection, which occurs as the overall conceptual theme of the activity. The students are to understand that natural selection occurs on the basis of differences between the individuals of a generation. The only parameter for selection is the "fitness" of the individual animal; 2) Fitness, which is presented to the student so that they will be able to see that fitness is a concept attached to the whole organism and not to single genes. The students will have the opportunity to see that there is no such thing as a good gene or a bad gene but there are good combinations of genes and bad combinations of genes; 3) Genetic drift, in which students see genes drifting out of the population and not returning due to the small cohorts in the activity.

In this section we identify some opportunities for assessment of inquiry skills. Some tools for formative assessment are proposed, aimed at verifying the development of inquiry skills of planning investigations and forming coherent arguments. This unit also provides a key opportunity to strengthen students’ scientific reasoning capabilities and enrich their scientific literacy. Several assessment opportunities have been identified, and some criteria for assessment detailed for these skills.

As pointed out in many of the case studies this activity is very time demanding and in all cases was run over several lessons. In one of the case studies it is suggested that the activity could be run in e.g. a volunteer after-school course where the students have the possibility of staying within the activity without having to unpack and pack materials from lesson to lesson and thereby getting a more continuous flow in motivation, knowledge and skills during the activity.

Another extension could be to incorporate the digital simulation more after having run the activity. This would give the possibility for further discussion the impact of the different biological concepts. This discussion could contribute in the development of the skills of debating with peers and forming coherent arguments.

Below you can find the full inquiry and assessment unit for download, as well as an archive with classroom materials, including student worksheets and assessment tools for teachers to be used during the activities if available.

Unit booklet Classroom materials

Activity A: Natural selection

Concept focus	Visualising evolution
Inquiry skills focus	Planning investigations Forming coherent arguments Working collaboratively
Scientific reasoning	Data entry and observation skills Organisation and interpretation of data
Scientific literacy	Understand how the model legorgs relate to evolution Analysis of data and presentation of scientific results
Assessment methods	Classroom dialogue Teacher observation Worksheets Student devised materials Other assessment items

The Legorgs consists of six segments – representing a gene with five alleles indicated by different colours of the bricks. Each allele specifies a morphogenetic rule for how the segments are placed. The students work with this physical model including multiple genes, making it easier to understand concepts like “fitness,” “natural selection” and “genetic drift.” In this exercise one of the main limitations of the model is that the measurement of “fitness” relies only on one parameter, namely the moving length of the Legorg when falling.

This unit was trialled in four countries, producing five case studies of its implementation (CS1 Poland, CS2 Hungary, CS3 Denmark, CS4 Sweden and CS5 Hungary). In all the case studies, the teachers had some previous experience of teaching through inquiry. However, the students involved had varying levels of experience of being taught through inquiry.

This unit was recommended for implementation at upper second level, however teachers in CS1 Poland and CS4 Sweden implemented this with lower second level students, aged 14-16 years. The students in the described each of the case studies are of mixed ability and mixed gender. In CS1 Poland, CS3 Denmark and CS4 Sweden, the student groups consisted of 4-5 students. In CS2 Hungary, the specific study group size is not reported, but the class consisted of five groups of mixed gender and students with dyscalculia were placed in a teacher assigned group. In CS5 Hungary, the class consisted of 15 students, but again, group size is not specified. In CS3 Denmark, the activity was implemented in either one 180-minute lesson or two 90-minute lessons, while in all other case studies the task was allotted 4-5 lessons of 45-minute duration.

The key skills assessed in the case studies were forming coherent arguments, planning investigations and working collaboratively, while opportunities for assessment of scientific reasoning and scientific literacy were also identified. The key assessment method was provision of formative feedback through classroom dialogue, as well as evaluation of student worksheets or student-devised materials.

In all cases the inquiry approach used was guided inquiry, as detailed in the original unit. All groups worked with the same research question and the same methodology, using the resources from the draft unit or online. However, due to the in-built randomness of the task the students got different results from their investigations. Teachers have noted that this activity is quite structured, as the process is outlined step by step in the unit, but that implementation is open as the students have many opportunities to engage in open questioning and interpretation.

There were variations in how the unit was delivered in the different contexts. In general, students had received lessons in the biological concepts of natural selection, genetic drift and fitness beforehand. However, in CS4 Sweden, the unit was adapted for lower second level students and focused only on natural selection, omitting the concepts of fitness and genetic drift. To commence the lesson, the students watched a video (in Swedish) about evolution.

In all case studies, the students worked in randomly organised or student-selected groups, except for a teacher assigned group of students with dyscalculia in CS2 Hungary. There were some differences recorded in terms of group size and how they were organised. The group sizes ranged from 3-6 students.

In the five case studies, many focused on planning investigations and working collaboratively, as well as forming coherent arguments and enhancing scientific literacy and scientific reasoning capabilities. There was a common understanding across all case studies that this exercise is particularly good for developing skills in working collaboratively and forming coherent arguments, although this is only possible if students are given time to work through the exercise.

In all case studies, the teachers provided formative assessment in-class, carrying out on-the-fly evaluations of student performance. In CS5 Hungary, the teacher notes that in the initial phase of the activity there was not a lot of time to assess the students, but in the later phase there was time for observation and assessment.

Below you can find the full inquiry and assessment unit for download (excluding the case studies), as well as an archive containing all the case studies.

Unit booklet Case studies

CS1 Poland

Concept focus	Construction of legorgs and measurement of “fitness” as a model for natural selection
Activities implemented	Natural selection
Inquiry skills assessed	Planning investigations Forming coherent arguments
Scientific reasoning	Data entry Drawing conclusions
Scientific literacy	Understand how the model legorgs relate to evolution Analysis of data and presentation of scientific results
Assessment methods	Classroom dialogue Teacher observation Worksheets Other assessment items
Level	Lower
Age	15
Prior experience with inquiry	No experience

In this implementation at lower second level, a creative solution was found to use of English resources – a class was dedicated to translation, which also allowed for introduction of the topic. Scientific literacy was the key skill assessed, looking at students’ analysis of data, numerical and statistical interpretation and ability to transfer the model system (legorgs) to real-world understanding of natural selection. Assessment methods include teacher observation in-class and a pre/post test.

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CS2 Hungary

Concept focus	Evolution of legorgs as a model for natural selection
Activities implemented	Natural selection
Inquiry skills assessed	Planning investigations Forming coherent arguments
Scientific reasoning	Organisation and interpretation of data
Assessment methods	Classroom dialogue Teacher observation Worksheets
Level	Upper
Age	15
Prior experience with inquiry	Very experienced

This case study details implementation in an alternative secondary school, with students’ ability ranging from those in an advanced maths class to students with dyscalculia. The teacher evaluated students’ skills in planning investigations and forming coherent arguments, and their scientific reasoning capabilities, in particular through collection and interpretation of data. Assessment was guided by performance levels in the teacher’s scoring rubric, and the students’ received oral feedback on their work.

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CS3 Denmark

Concept focus	Construction of legorgs and measurement of “fitness” as a model for natural selection
Activities implemented	Natural selection
Inquiry skills assessed	Forming coherent arguments Working collaboratively
Assessment methods	Classroom dialogue Teacher observation Worksheets Student devised materials
Level	Upper
Age	15-18
Prior experience with inquiry	Very experienced

This case study details the findings from three separate implementations, with students aged 15-18 years. A key skill identified for assessment was forming coherent arguments, which was assessed through evaluation of student worksheets or reports. Assessment of working collaboratively was also achieved through teacher observation in the classroom and evaluation of video recordings of the lessons.

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CS4 Sweden

Concept focus	Natural selection – evolution of legorgs
Activities implemented	Natural selection
Inquiry skills assessed	Planning investigations
Scientific reasoning	Data entry and observation skills
Assessment methods	Classroom dialogue Teacher observation
Level	Lower
Age	14-16
Prior experience with inquiry	Some experience

This case study details implementation with three lower second level classes. Adaptations were made to account for this level of prior knowledge, and to overcome difficulties due to insufficient quantity of Lego®. One class utilised computer simulations as a complementary process. Assessment focused on planning investigations and scientific reasoning, with classroom dialogue and teacher observation used to good effect.

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CS5 Hungary

Concept focus	Construction of legorgs and measurement of “fitness” as a model for natural selection
Activities implemented	Natural selection
Inquiry skills assessed	Planning investigations Forming coherent arguments Working collaboratively
Assessment methods	Classroom dialogue Teacher observation Worksheets
Level	Upper
Age	18-19
Prior experience with inquiry	Some experience

In this case study, final year students volunteered to participate in the inquiry activity held over five lesson periods. Skills identified for assessment were planning investigations, working collaboratively (debating with peers) and forming coherent arguments, evidenced by students’ ability to collect and analyse data, and interpret relationships. Assessment was primarily through formative feedback during classroom dialogue, and the teacher used rubrics to identify performance levels.

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Natural selection

Is fitness in the gene or in the animal?