This DNA extraction lab is a classic one! You can use any grocery item such as onions or peas, but frankly, the color and smell of the strawberry lab is much more appealing to work with.
I use this lesson as a curiosity builder; kids love the procedure of banging the baggies of strawberries and using funnels and other lab equipment. The directions are very straightforward and there is an explicit connection between the pre-lab summary of information and the analysis questions students are asked to discuss. The lab does not require a lot of prior knowledge about DNA and generates many content questions and connections both during the session and beyond.
There is a brief question at the end that requires students to dig a bit deeper into the definition of a nucleotide however, overall the goal is provoke interest, generate questions, and enjoy lab procedures that are interactive and related to materials they are already familiar with in their daily lives.
1. Tell students that today you will be working on a DNA extraction lab activity.
2. Using the spokesperson protocol, ask student lab groups to discuss the following prompts:'
What does the word extraction mean?
How do you think we could extract DNA?
3. Share out group responses. Typically students will be able to tell you that to extract something means to take it out. They will not have a clear idea about how to do that--they will guess that it happens in a lab and that scientists do it with blood samples.
4. Tell students that today they will be extracting DNA themselves using simple materials from the grocery store and samples of strawberries for each lab table. Show students the strawberry DNA extraction materials they will be using.
1. Show students where the materials of the lab are located and the individual lab table equipment set ups they will be using.
2. Ask student groups to assign the following roles: project manager, clean up and safety, data/observations recorder, and research librarian.
3. Once student groups have determined their individual roles for the lab activity and their overall plan, they may move to their lab tables and begin their activity.
4. This will be a noisy time for the first ten minutes of class as students bang on their baggies to pulverize their strawberry samples and enjoy the science play aspect of this lab procedure.
5. This section of the lab activity is busy and may require your assistance as students determine the right technique to use as well as work with their funnel apparatus. Overall, you will find students will be engaged and productively busy.
6. You will see many examples of productive, on task collaborative work throughout this engaging session:
1. Students will settle into a quieter space as they observe their funnels and wait for their samples to be ready for extraction. There will be three basic phases:
2. Once students begin extracting their DNA, be on hand to encourage and congratulate! The kids love that type of feedback from their teachers especially during lab situations. It is a great opportunity to build community and connections as you share a common interest and collaborate to accomplish a task.
3. As students begin to clean up their materials and return to their lab tables to work on their analysis questions, remind students that they can be working on their lab observation/analysis questions as a team or looking up nucleotide definitions and diagrams in preparation for the last question on the lab document.
1. With the remaining time, ask student groups to think of one big question they have about DNA and list it on the board for public viewing. Some potential student questions include:
How do scientists figure out what genes are on each chromosome?
Can scientists take out or add in genes to cure diseases?
How does DNA get mutated?
2. Let students know that this is an important unit of study that we will be spending a lot of our time on and that our goal is to explore all of their questions together as a team!
3. Check out this example of student work for this activity. Students should be able to summarize the purpose of each material use in the extraction technique and to draw a detailed drawing of a segment of DNA.