For Teachers - Hacking the Code

Indications for Teachers

This activity deals with the genetic code in an IBSE (Inquiry-Based Science Education) approach, and is directed to secondary school 14-18 years old students. As you can see, the site is directed to students, so you can propose them directly the web address to undertake the activity. However, you are strongly recommended to print the materials offered and give them to the students along the activity.

Publications

This activity and its didactic outcomes are described in two published articles:

Cracking the genetic code: replicating a scientific discovery. Science in School (2016), 36, 47-51. J.Domènech-Casal.
Hacking the code: una aproximació indagadora a l'ensenyament del codi genètic, o seguint les passes de Nirenberg i Khorana. Ciències (2013) 25, 20-25. J. Domènech.

An extended version including key experiments on DNA discovering with students' materials is available in Catalan (see downloadable materials below).

This activity is part of the educational C3 Project (Creation of Scientific knowledge) and the Syllabus ABP/IBSE Itinerary ProyectandoBioGeo. Comments and suggestions are welcome. If you add or modify steps from this didactic sequence, please, let me know, your work can be useful for other teachers and students. If you want, I could eventually add your activities as a contribution in this website, together with your name and contact details.

Indications to Apply the Activity

Use this activity as an introduction, before explaining anything about the genetic code or the central dogma of molecular biology.
Don't explain anything to your students. Don't tell them about the biological nature of the sequences (DNA and peptides). Focus them on finding patterns and relationships. Simply furnish them with the sequences and ask them to find out how it works. You don't even need to tell them to look for a code. They will be able to learn it alone. Just let them work, and observe their discussions. You'll have the opportunity to collect the explanations after and from their work.
Let them talk between them, even between the different teams. Science is a social process. Scientists don't call it copying or cheating. They call it constructing knowledge, and it usually happens in congresses and seminars.
At each step of the process, you can ask one student from each team to join another team. This is how real science works: researchers change from one team to another to expand and increase knowledge. If you do so in each step, it is possible for a team to arrive at a general conclusion based on the work of members that are no more in the team.
Ask your students to think. Explain them you expect their best.

About IBSE (Inquiry-Based Science Education)

Some of the principles of IBSE used to build this site and the didactic activity:

Scientists generate scientific theories based on evidence, but they do not find definitive answers. Real science has not a book of "correct answers" where you can contrast if your conclusions are correct. "Correct processes" and "Best explanations" is the most you can get in real science. It's why I don't recommend to add a "correction" part in the exercise to contrast if their answers are correct.
Scientific knowledge and ideas change over time and are open to further revision as our understanding of the world around us evolves. Education doesn't mean to transmit a false feeling of certainty. Education means to teach how to deal with uncertainty, to take decisions and assume risks. In case of misunderstandings, just ask them if their process is correct and their results coherent. Answer with questions to their questions, or help them to make better questions. "Correct solutions" or "Wise teachers" won't be present in their life for ever. Teach them how to do without it.
Science is a social and creative activity. Constructing and testing hypothesis, interpreting data from different formats and adjusting an abstract model as a consequence, identifying patterns and establishing relationships, discussing results and justifying conclusions, are key competences that science learning must include as a priority, not only to make them best scientist, but to make them critical citizens.

Calendar and Sessions

The activity takes 1h - 1:30h, depending on the length of the final session.

Evaluation and Exam

In this activity, attitudes, reasoning and constructing knowledge skills are developed. My advice is to follow the final session and mark the good participations of the students in the debate. Let them know that you will do it, and that you will mark only significant participations.

If you prefer more traditional evaluation tools, ask them to present you the notes they have taken during the activity.

Attention to Diversity

How to make easier the work for a team:

Give them more sequences (sequences from two Teams).
Suppress steps 3 or 4.

How to make harder the work for a team:

Add the corresponding RNA sequences.

A Spanish version of the site is under construction and will be soon available.

CLIL/AICLE

This site has been built from a didactic activity performed with Spanish students. Linguistic clues are in development.

Hints and Ideas for Further Development

You can use similar approaches to make students discover aspects as: the codon usage, the different Open Reading Frames.
Including in each step RNA sequences or unrelated sequences could be interesting, as students should discriminate informative from non informative data, and find different explanations to the data.

References

This activity is inspired on the original research work of Nirenberg and Khorana, who in 1965 discovered the genetic code by making associations of artificially synthetized poly-nucleotides to their corresponding peptides.

NIRENBERG M., LEDER P., BERNFIELD M., BRIMACOMBE R., TRUPIN J., ROTTMAN F., O'NEAL, C. (1965). RNA codewords and protein synthesis. On the general nature of the RNA code. Proceedings of the National Academy of Sciences U.S.A. 53(5): 1161–8.

DOMÈNECH, J. (2013) Hacking the code: una aproximació indagadora a l'ensenyament del codi genètic, o seguint les passes de Nirenberg i Khorana. Ciències: revista del professorat de ciències de primària i secundària, 25, 20-25.

Download Printable Materials

Here, a list of the materials for the students, grouped by Teams. Don't give them the information for all the steps at the same time. Give them the information for each step after their work on the previous step during 5 minutes.

Hacking the Code