Physiological Determinants of Global Health

Classroom Activities

In Virginia, third grade science emphasizes how we can characterize living things. We build on students’ prior knowledge that organisms have needs that must be met in order to survive. This unit will integrate that major theme in several activities. First, students will brainstorm how we can distinguish living things from nonliving things. I want students to realize that living things have common needs for survival. This will lead to the question, “Why do living things need water, air, and food (nutrients) to survive?” I will display a photo of a cell, and explain how we are made of billions of cells. To help students understand the concept of billion, trade books such as “How Much Is A Million?” by David Schwarz and “Big Numbers” by Edward Packard could be used to provide visual references. Next, using the photo of a cell, I will explain to students how multicellular organisms (such as humans) start as one cell. It may be helpful to have students generate a list of living things in order for them to understand the impact of cellular reproduction.

Once students are aware of the cellular composition of organisms, I will display photos of a cell and a student in the classroom. I will ask students, “How did this one cell develop into a person?” I will explain that a blueprint is necessary to build things and provide actual copies of blueprints from different objects such as homes, electronic items, and toys. I will discuss how our cells have blueprints to continue to reproduce, and inform students that the blueprint for cellular reproduction is called DNA.

While displaying the DNA diagram from Figure 1, I will explain how DNA is made of different chemical components. I will provide students with an opportunity to think of a common object similar to the structure of DNA. It may be useful to ask the school maintenance team for permission to view a ladder in the building. I will inform students that DNA, like a ladder, has rungs and a backbone. Using Figure 1, I will explain to students how four chemicals are paired together to make the rungs of the ladder. A kinesthetic activity can be used to show students how the pairings are always the same in DNA structure. To accomplish this, students are provided with index cards labeled with the words adenine, thymine, cytosine, or guanine. At the cue of music, students have to find their appropriate partner based on their card. This will provide students with a visual aid in understanding how DNA is formed.

After the activity, I will ask students to find a partner for a portrait activity. Students will draw the face of their partners, and discuss the similarities and differences noted in their drawings. I will ask students, “Why do we have different colors of eyes? Why do some of us have wavy hair, while others have straight hair?” This will provide students with the opportunity to reflect how DNA acts as a blueprint for our cells. I will explain to students that our cells have different specializations the same way that people specialize in different jobs. It may help to provide students with specializations, such as how a firefighter is unable to switch places with a dentist. This example can be used to show students that our DNA tells cells what jobs they will perform in our bodies. DNA determines if we will have certain traits, or characteristics. The book, “Grandfather’s Nose: Why We All Look Alike or Different”, can be used to provide students with a text-to-self connection. The book, written by Dorothy Hinshaw Patent, helps students to understand that not DNA is responsible for our traits. It also provides illustrations to explain how DNA acts a blueprint from our parents to determine our physical features. After reading the book, the interactive Family Portrait activity located at www.dnacenter.com gives students a hands-on opportunity to learn more about inheritance of features.

Students can also experiment with DNA extraction to understand how the blueprint is found in living organisms. First, to show students that humans possess DNA, we will extract it from cells obtained from the inside of the cheek. Next, I will ask students to hypothesize if DNA would be present in strawberries. This activity allows students to substantiate why we would find DNA in strawberries by forming a hypothesis. For example, they may support their thinking by arguing that plants are living things, so the fruit would possess DNA. Students can work in pairs and follow a handout to extract the DNA from the strawberry.

The extraction of DNA from various organisms can be used as a springboard to the use of GMO crops. I will ask students, “Is it possible to mix the cheek DNA with the strawberry DNA?” They should be able to support or defend their positions. I will mix the two DNA samples together, and inform students that scientists are able to mix DNA from different organisms. I will display a photo of a malnourished child, and ask the class what could be the causes of the child’s condition. Next, I will explain how nutrition can determine the health of an organism, and ask students, “Why is it easy for us to improve our diets?” This will help students to understand how the availability of food allows us to choose what we can eat in America, but how other regions have limited choices. I will display a photo of rice, and ask students, “If this is the only food source the malnourished child has, what could be done to make sure he or she is healthy?” We will brainstorm what could be done to the rice to make it a super food for the malnourished child. I will display examples of GMO crops such as golden rice or insect resistant corn. I will explain how scientists mix DNA from different organisms to improve the rice or corn, and allow students time to research examples of GMO crops from KidRex. The students can also create a cause and effect diagram to show how the crops improved the health of people.

As a finished product, the students will be given a region in the world, and a scenario describing a vitamin deficiency or malnutrition found in the area. Students will have to research a local plant that could be used to address the deficiency or malnutrition. What would they have to add to improve the nutritional content of the crop? Describe how the weather conditions and soil type could help with the growth of the crop. Does the crop need a specific soil type to grow? Why would they select a crop that is hardy and able to sustain various weather conditions or pests, versus a crop that has specific needs in order to be sustainable? The students will create an advertisement, flier, or power point to persuade farmers in the area to grow the crop.

My goal is to use the content information and classroom activities to show students the benefits of bio-fortified crops. I want to also show students the opposition to GMO crops, and provide them with opportunities to understand why it is important to distinguish facts from opinions. We can use kid-friendly search engines to locate informative websites, and to determine why some websites may not be factual. I think it is important to help learners understand how to collect and analyze information on their own. It is vital for our students to recognize the need to process information and determine its relevance.