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Scratch, a visual programming language, was used in many studies in computer science education. Most of them reported positive results by integrating Scratch into K-12 computer courses. However, the object-oriented concept, one of the important computational thinking skills, is not represented well in Scratch. Alice, another visual programming language, seems to have better illustration of the object-oriented concept for programming novices. To demonstrate effects of Alice and Scratch, we compared students' responses to both visual programming languages, especially for students with low performances, in an introductory programming course. The relationships among learning engagement, learning anxiety, and learning playfulness were explored. The results could be referred to by computer science instructors to select proper visual programming language for corrective instruction.

Several superconducting transition temperatures in the range of 30–46 K were reported in the recently discovered intercalated FeSe system (A1-xFe2-ySe2, A = K, Rb, Cs, Tl). Although the superconducting phases were not yet conclusively decided, more than one magnetic phase with particular orders of iron vacancy and/or potassium vacancy were identified, and some were argued to be the parent phase. Here we show the discovery of the presence and ordering of iron vacancy in nonintercalated FeSe (PbO-type tetragonal β-Fe1-xSe). Three types of iron-vacancy order were found through analytical electron microscopy, and one was identified to be nonsuperconducting and magnetic at low temperature. This discovery suggests that the rich-phases found in A1-xFe2-ySe2 are not exclusive in Fe-Se and related superconductors. In addition, the magnetic β-Fe1-xSe phases with particular iron-vacancy orders are more likely to be the parent phase of the FeSe superconducting system instead of the previously assigned β-Fe1+δTe.