Where It Comes From: All About Heredity
Characteristics are not only inherited, but can be acquired through interactions with the environment.
By Bruce Howard
Are freckles inherited? How about wrinkles? How do we determine such things? In this article, I will provide some ideas for teaching the following concept: some characteristics are inherited while others result from interactions with the environment.
With fifth graders, it may be too ambitious to get into genes, chromosomes, DNA, and particulars of sexual/asexual reproduction. These topics require much more of a foundation and are best left for seventh grade to wait to cover in any depth. At this age, you want to stick to the basics:
- How is genetic material passed between generations?
- What is the difference between an inherited characteristic and one that develops as a result of interactions with the environment?
Taking the Right Approach
There are several approaches you may want to consider. The main thing is that you want your children to make observations between parents and offspring; ideally both in animals and plants. They should observe that certain traits in the offspring resemble certain traits found in each of the parents. Some lessons are geared toward having children go home and survey family members, including grandparents, with a list of these items:
- hair color
- eye color
- right-handed/ left-handed
- right-eye or left-eye dominant
- length of index finger compared to ring finger (or toes)
- straight or curly hair
- attached ear lobes
- ability to curl tongue
With other lessons, you may examine fruit flies or peas under a microscope. There is a great activity described below where you can research a horse and its lineage.
With each of these approaches, the students will first focus in on the most obvious and observable physical characteristics. You’ll recall that at this age, one of the science process skills we are teaching is observation. In order to probe further, talk about other traits that are not so observable, and have your class propose some too. For instance, a sense of humor, how many hours of sleep someone needs, speed (with dogs or horses), aggression, disease resistance (chickens), number and size of fruit (plants), or drought tolerance. Discuss selective breeding and how the scientific method can help to determine the best kinds of crops, fruit, dog breeds, horse breeds, fish flavor, etc.
Whenever your class encounters a trait that may not be inherited, write it in a special area on the whiteboard. We will use this list next. This is an area where science does not have all the answers (yet). That is, what is the difference between an inherited characteristic and one that develops as a result of interactions with the environment?
The Influence of the Environment
Go back to your set aside list. Use this list to show that some traits are not so easily shown to be inheritable. This is a good opportunity to reinforce inquiry skills and the scientific method. Brainstorm with your class how you would go about proving or disproving, whether a particular trait is inheritable. Pick a few obvious ones and have students conduct some online research to see if anyone has ever studied them.
Where You're Headed
Here are the key concepts you will want to cover:
- Because offspring resemble their parents, there must be a means for transmitting information between generations.
- Offspring resemble their parents in some ways, but not others.
- The characteristics of organisms are influenced by what they inherit and the environment.
- Similarities among the characteristics of offspring and parents are indicative of traits that are inherited.
- Certain acquired traits result from interactions between an organism and its environment.
- Characteristics such as the ability to ride a bicycle are learned and cannot be passed on to the next generation.
The following lessons provide a starting place to develop your own lessons around this topic:
This resource provides a lesson that includes data collection and inquiry. Pupils will collect data from family member and draw conclusions about inherited traits. The result is that they will understand that physical traits can come from family members.
All materials are self-contained in this lesson. Young scientists examine three generations of horses and their traits.
This short lesson provides a great list of traits for a family survey.
Using observations about peas, your class will be able to see how physical characteristics are determined by biological and environmental factors. For example, the color and texture of peas are passed on from parent peas, but the size can be determined by where the pea is located in the pod. Additional information is included and can be utilized, depending on grade level.