Teaching Heredity K-8
Heredity is the study of how characteristics are inherited. It is a multi-faceted topic which can be found in many areas of the life sciences. For example, it explains why some features, including inherited diseases, exist in families; the mechanisms of evolution by natural selection and how lifestyle factors such as smoking can lead to cancer.
In the long term, an understanding of human genetics is vital for students to live as informed citizens in the modern world. A good foundation will help them to make decisions such as whether they should worry about GM food or if a genetic test should be carried out on them or a member of their family.
Where is heredity in the NGSS?
The NGSS is content with progression. This means that students will come across key scientific ideas time and time again, and they will be expected to build on their knowledge to form a layered understanding of the topic.
The various aspects of heredity are taught in the Core Idea LS3: Heredity: Inheritance and Variation of Traits, which is divided into two sub-ideas: LS3.A and LS3.B. Let's take a closer look at what students are expected to learn at each stage in their education.
LS3.A Inheritance of traits. The underpinning question that this core idea answers is 'How are the characteristics of one generation related to the previous generation?'
Grades K-5: At the start of elementary school, students look at how organisms vary and recognize they look a bit like their parents but not identical. In grades 3-5 they learn that many characteristics of organisms are inherited from their parents, whilst others result from the environment.
Grades 6-8: By the end of grade 8 it is expected that students can start to link ideas about reproduction and genes to the characteristics of organisms. They will understand how pairs of genes passed to an offspring via sexual reproduction control the production of proteins. They will see how variation between parent and offspring arise from different mixtures of genes and (more rarely) from mutations.
Grades 9-12: In high school, students will learn that chromosomes consists of DNA, and each gene on the chromosome is a particular segment of that DNA.
LS3.B: Variation of traits. This seeks to answer 'Why do individuals of the same species vary in how they look, function, and behave?'
Grades K-5: Students will learn that offspring acquire a mix of traits from their biological parents which is due to inherited information.
Grades 6-8: During this stage, students learn that during sexual reproduction the offspring acquire two of each chromosome and hence two alleles of each gene from both parents. They see how these versions may be identical or may differ from each other.
Grades 9-12: By the end of grade 12, it is expected students will understand that the information passed from parents to offspring is coded in the DNA molecules that form the chromosomes.
You can see from these descriptions how the same important concepts are repeated and how progression is built from kindergarten right the way through to senior year. To make this transition smooth it is vital that all students are able to fulfil the performance expectations before moving onto the next level.
Unfortunately, despite its importance in both student's lives and the curriculum, heredity is a topic that many students find difficult. One of these reasons is that it contains specific vocabulary that often sounds similar but has very different meanings, for example: genes, alleles, phenotype, genotype, homozygous, heterozygous. Also, the concepts are abstract so children cannot physically see how the mechanisms of genetics works.
Unfortunately, it can have a reputation for being a 'dry' topic with not many opportunities for the practical work and hands-on learning activities that students enjoy. This is where SciTT Kits can help. We have come up with a number of interesting activities for teaching heredity which we have used to create our kits. Let's have a look at two of these kits in more detail.
The SciTT Kit 'Genetics And Heredity' is suitable for students grade 5 and above and contains activities that can be used to cover many aspects of LS3 up to year 12. The variety of activities it contains are designed to make the difficult concept of inheritance not only accessible for students but fun as well.
In the first activity, students work in groups and follow simple instructions to build their own organism based upon specific genetic traits. They are introduced to the concept of dominant and recessive versions of genes and model the allocation of these genes in reproduction. Depending on which discs they randomly choose, they build their model with features such as a large or small head, thin or thick legs and green or black wings. They will learn that from a set of genes from the same parents, many variations of offspring can be produced. This group modelling activity makes this abstract process visible and greatly aids understanding.
The kit also contains background information explaining the key terms, assessment and discussion ideas for teachers as well as activity sheets which take students through how to use Punnett squares.
In order for students to grasp the concept how DNA codes for proteins they must first know how bases are arranged in the DNA strand. The SciTT Kit 'DNA model' is an ideal way of introducing this and is also suitable for students from grade 5 all the way up to senior year.
Students use the materials in the kits to build a physical model of a DNA strand and learn about the different nucleotide bases and how these form the genetic code. Building a model in this way helps students to visualise the structure of DNA and how this relates to protein synthesis.