Teaching Resources

Adília Alcina Gonçalves Tavares da Silva

Escola Secundária/3 Abade de Baçal, Bragança, Portugal

Teacher from the network, author of the learning guide and responsible for testing the resource.

PhET

Radioactivity: beta decay, alpha decay, radioactive dating.

- Understand the concept of radioactivity.
- Identify radioactive isotopes.
- Schematically represent the radioactive decay of some nuclides.
- Determining the period of decay from the half-life time.
- Apply this knowledge to the dating of objects with hundreds or thousands of years.

The simulations can be downloaded from the website and used offline. The resource is available in several languages, namely, in English and Portuguese.

Escola Secundária/3 Abade de Baçal (Bragança, Portugal), upper secondary school, 12th year (17 years), Chemistry discipline (optional), with 17 students.
This methodology started in 2010/2011 and was repeated in the subsequent years in classes where the number of student rose constantly. Nowadays, the class is constituted by 30 students.

1. The digital resource was explored by students, following the instructions described in the learning guide presented in the supporting info.
2. Pupils in the class, divided in groups of 2 elements, explored the digital resource answering the challenges proposed in the learning guide.
3. Both students discuss the results as a group but each one gives an individual written answer.
The work was carried out in a classroom equipped with one computer for each group of 2 students.

- Students did not find difficulties in using the digital simulations, understanding the contents and using the information to answer the challenges proposed in the learning guide.
- They showed cooperative attitudes.

A two stage analysis was performed to assess the students’ learning progress. A pre-test was held before the simulations application and the results were recorded. After the contacting with this methodology, a post-test was given to students and the results were compared to the pre-test. The gains were determined, allowing the formulations of the following comments:
i) The highest classification in the pre-test was 60% while in the post-test was 96%.
ii) The lowest grade in the pre-test was 30% while in the post-test was 58%.
iii) On the pre-test, the average grade of the class is negative (46.2%) where only 7 students were able to score higher than 50%.
iv) The post-test results were significantly improved, where all the students were able to score positive grades, the lowest being 58% and the highest 96%.
v) Twelve students scored marks higher than 70% and the class average increased to 80.9%.
vi) The normalized gains calculated through the comparison of both pre- and post-test demonstrate a high conceptual gain of the class (averaging 0.64) and for each individual student, since 82.35% of them were able to obtain gains above 0.50.
Therefore, the application of computer simulations is a useful and effective resource when explored within the framework of a learning guide. The learning guides are important mediation instruments that support the student on the construction of knowledge.