Teachers’ reflections on non standard students work

One of the tasks of teaching (Ball, Thames, & Phelps, 2008) concerns the work of interpreting student error and evaluating alternative algorithms used by students. Teachers’ abilities to understand nonstandard student work affects their instructional decisions, the explanations they provide in the classroom, the way they guide their students, and how they conduct mathematical discussions. However, their knowledge or their perceptions of the knowledge may not correspond to the actual level of knowledge that will support flexibility and fluency in a mathematics classroom. In this paper, we focus on Norwegian and Portuguese teachers’ reflections when trying to give sense to students’ use of nonstandard subtraction algorithms and of the mathematics imbedded in such. By discussing teachers’ mathematical knowledge associated with these situations and revealed in their reflections, we can perceive the difficulties teachers have in making sense of students’ solutions that differ from those most commonly reached.

Germination requirements of Plantago algarbiensis seeds, an endangered species endemic to the Algarve region (South of Portugal)

The ecdysteroid, 20-hydroxyecdysone or beta-ecdysone, is a steroid hormone which plays a crucial role in molting, metamor- phosis and reproduction of arthropods. This ecdysteroid and its analogues have high potential to be used as insecticides. Previous studies in our laboratory have demonstrated that Vitex glabrata R.Br. (commonly known as Khai-Nao), an indigenous herbaceous plant of Thailand, synthesized and accumulated high quantity of 20-hydroxyecdysone. Therefore, the aim of this study was to investigate the effect of precursor and elicitors feeding on cell growth and 20-hydroxyecdysone production of V. glabrata suspension cultures. Plant cells were cultured in half strength MS medium containing 30 g/l glucose and supplemented with 2.0 mg/l 6- benzylaminopurine (BAP) and 1.0 mg/l 2,4-dichlorophenoxyacetic acid (2,4-D). Cells were incubated on a rotary shaker at 120 rpm under continuous light of 2000 lux at 25 °C. Sterilized cholesterol (5 and 10 mg/l) as precursor was added to the cell cultures on the day of inoculation, while chitosan (50, 100 and 200 mg/l) and methyl jusmonate (100 and 200 mM) as elicitors were added to the cell cultures on day 6 after cultivation.

In vitro spore germination of Polystichum drepanum, a threatened fern from Madeira Island

Polystichum drepanum (Sw) C. Presl is a threatened fern endemic to a few forest areas in the north-west of Madeira Island. The aims of this work were to establish suitable culture conditions for in vitro germination of spores, and to evaluate short-term storage conditions for P drepanum spores. The highest frequency of germination was obtained in Murishage and Skoog (MS) liquid medium, without agitation. However, gametophytes maintained in MS liquid medium did not grow and, after 4 weeks, became anoxic and died. Thus, after germination in liquid medium, gametophytes were transferred to an MS double-phase culture system for further growth. The effects of storage period, temperature, and relative humidity during storage on in vitro spore germination were studied. Spore viability was assessed after 2, 4 and 6 months, and high viability (> 94%) was observed in all the assays. However, germination capability decreased with increased storage periods. The number of sporophytes obtained also decreased with prolonged storage periods. The results indicate that spores of R drepanum stored for 4 months at 21 degrees C maintain high viability and high germination frequency. ne sporophytes obtained were acclimatised in a mixture of peat and vermiculite [2:1 (v/v)] under high relative humidity (90-95%). Seventy-five sporophytes were successfully acclimatised to ex vitro conditions and showed active growth in the glasshouse.