Warm-Up: Why is DNA relevant in our daily lives?
Allow student to “turn and talk” with a seatmate about the relevance of DNA for 2-3 minutes. Walk around and listen for the consistent themes that arise from the student conversations. The major reasons for relevance that arise from the students will likely be paternity, overturning of criminal convictions, conclusive evidence that someone committed a crime, or the value of DNA for the early identification of genetic disease. Debrief at the end of the discussion time and allow students to share their thoughts. If any key reasons are not identified, be sure to raise them before ending the warm-up discussion.
Build interest by reading aloud a current article about a medical advancement due to decoding DNA or an article about how DNA led to the exonerated an innocent person convicted of a crime. I chose an article about two mentally disabled brothers who served 30 years for a crime they did not commit. Allow students to share their thoughts about the information that they have just learned.
Further build interest and engagement by allowing students to watch a video, The Value of Evidence. Establish the viewing expectations before beginning the clip. This video can be found on the Discovery Channel teacher website.
Note: The minor inconvenience of having to register to utilize this site is minor in comparison to the useful information and other resources that teachers will find on this website.
After the clip ends, allow students to share their thoughts about any of the information that they have just learned. Listen as students share their thoughts. Encourage students to use sentence prompts to help initiate the discussion.
These two activities serve to engage students in the lesson and provide opportunities for them to identify the significance of DNA extraction.
Ask students if they think it is difficult to extract DNA from a cell. Expect that many of them will say that it is a difficult process. Listen to their comments then show students a video that shows them how easily they can perform a DNA extraction at home using household materials.
Inform students that they will engage in a virtual lab that will allow them to learn how to perform a cheek swab in order to extract DNA from human cells. The free website is Learn.Genetics.
In advance of the class, make sure that each desk has a laptop computer. This eliminates the use of class time for a distribution procedure. Instruct students step by step on how to access the learn genetics website. This is done because there are always a few students in a class who are not computer literate and need the detailed explanation of how to get to a website using an internet browser.
After you model how to access the website, make a quick circuit of the room to ensure that all students have successfully navigated to the correct page before continuing. Ask students to work as teams to check their neighboring student computers to see if their neighbors are on the correct page. Once you have ensured that everyone is on the correct page, explain and show students how to navigate the website, particularly how to advance from one page to another. Answer the first question of the lab, “Why do you need human DNA?” as a class. Look for students to be able to use the information they've learned to respond correctly to this question.
Distribute hard copies of the Virtual DNA Extraction Lab. Instruct students to read the lab instructions and questions before beginning the lab. It may be helpful to have students underline or highlight the questions as they pre-read the lab. This practice will help them progress through the lab slides with greater focus and intention about what is to be done and answered.
Instruct students to use their own paper to write their responses to the questions. Remind students to answer the questions using complete sentences. Give students 20-25 minutes to complete this activity.
Walk around as students work independently to complete the lab. Look for signs of difficulty, either navigating the site or responding to the questions. Provide assistance as needed. Consider ability grouping students who would benefit from working in pairs to ensure that everyone will be able to perform the tasks and complete the lab.
The student work samples show that students were able to gain an understanding about the process of DNA extraction and its value in identifying individuals. student work 1 and student work 2 both demonstrate an understanding of the DNA extraction process. Both students were able to use the evidence to correctly identify suspect #2 as the guilty party.
Perform a “whip around” where students quickly and verbally share one thing they learned in the class today. Look for students to identify reasons why scientists extract DNA, the benefits of DNA extraction and how it is performed.
Students should be able to explain that isolating DNA samples allows for body identification, genetic testing and forensic evidence.