Fun Approach to Teaching DNA Structure

Teaching AP Biology students has many challenges, one of them being that by the time my typical student reaches me they are 3 years removed form freshman biology. As much as they may tell you that they already know something, or “We learned this freshman year”, that does not always translate to “we REMEMBER this from freshman year”. Finding new and fun ways to reintroduce concepts to these students is a challenge that I enjoy.

I have the luxury of having a class set of the 3-D Molecular Designs “DNA Discovery Kit” models. This allows me to have each lab group (4-5 students) use their own kit in this activity.

First, I give the groups each a kit and tell them…well, very little.

I say:

Each group gets one “puzzle” and your challenge is to be the first group to successfully put it together. You must use every piece, and it must be free standing on the provided stand.

Then they begin. Now, I don’t even tell them that it is a model of DNA. Most of them figure that out (especially since it says “DNA model” on the box the model comes in) but knowing that it is DNA does not always translate to being able to quickly assemble the model. Students quickly figure out that they do not know the structure of DNA as well as they thought they did since the “already learned this freshman year”.

Many groups start by just fidgeting with pieces to see how they fit, nitrogen bases get paired up pretty quickly and then we hit some snags and the real learning starts to happen as they begin to problem solve. At this point, many groups will attempt various strategies to get the pieces on the stand. this helps them start to figure out how the components of the nucleotides fit together.

The most successful groups will put together full layers first (two full complimentary nucleotides) and then assemble them on the model. At this point they start to make comments about how each side seems to be pointed in a different direction! The groups that figure it out will then start to push through and their models come together quickly.

I will make sure the first group knows that they “won the race” and sometimes have a prize. Then I will begin to give a few suggestions or tips to the struggling groups to get them rolling.

New thing I did this year:

After everyone is done, I had them all look at their model with a piece of paper and pencil and BY THEMSELVES write down 8 characteristics of DNA that their model shows. This gets challenging once they get to 6 or 7. Next, they work in their groups to create a master list of 10 characteristics. Third, I have them infer a purpose for each characteristic. Finally, I will have the group choose what they feel is the most important characteristic and then share that with the class. This is a good opportunity to have a more guided discussion with the class about the characteristics of DNA and the reasons or purposes for these characteristics.

In my experience, this is an activity that the students seem to enjoy AND students do tend to reference the model in subsequent class periods as they work further through our molecular genetics unit and evidence from student assessments supports that this at least has not discouraged student understanding.

This year, after the activity I had a student very excitedly ask if they could put ALL them models together into one BIG strand. YES, of course we can do that! It …sort of worked. (Pictured at the top)