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Programming-by-demonstration (PBD) makes it possible to create web scraping macros without writing code. However, it can still be challenging for users to understand the exact scraping behavior that is inferred and to verify that the scraped data is correct, especially when scraping occurs across multiple pages. We present ScrapeViz, a new PBD tool for authoring and visualizing hierarchical web scraping macros. ScrapeViz’s key novelty is in providing a visual representation of web scraping macros-the sequences of pages visited, generalized scraping behavior across similar pages, and data provenance. We conducted a lab study with 12 participants comparing ScrapeViz to the existing web scraping tool Rousillon and saw that participants found ScrapeViz helpful for understanding high-level scraping behavior, tracing the source of scraped data, identifying anomalies, and validating macros while authoring. 

Peer assessment, as a form of collaborative learning, can engage students in active learning and improve their learning gains. However, current teaching platforms and programming environments provide little support to integrate peer assessment for in-class programming exercises. We identified challenges in conducting such exercises and adopting peer assessment through formative interviews with instructors of introductory programming courses. To address these challenges, we introduce PuzzleMe, a tool to help Computer Science instructors to conduct engaging in-class programming exercises. PuzzleMe leverages peer assessment to support a collaboration model where students provide timely feedback on their peers' work. We propose two assessment techniques tailored to in-class programming exercises: live peer testing and live peer code review. Live peer testing can improve students' code robustness by allowing them to create and share lightweight tests with peers. Live peer code review can improve code understanding by intelligently grouping students to maximize meaningful code reviews. A two-week deployment study revealed that PuzzleMe encourages students to write useful test cases, identify code problems, correct misunderstandings, and learn a diverse set of problem-solving approaches from peers.