At SIGCSE 2022 we reported on a grant funded CSforAll project to develop comprehensive and sustained college-high school partnerships focused on building computer science (CS) teacher capacity and broadening participation in high school CS classrooms. The partnerships involve a wide range of districts including high-needs and small rural ones. In this paper we first provide an update on this distinctive and successful project. Grant funding ended in 2022, however the project continues to grow and evolve. Led by faculty at a small liberal arts college, some of the results are stunning and demonstrate the impact a small college can have. For example, in the last three years the number of partner school districts has increased from 23 to 54. The teacher retention rate is 95%, with the most veteran teachers belonging to the partnership for almost ten years. This update includes two additional years of data on student experiences in their CS classes. Second, we provide suggestions and encouragement for replicating this work. The project provides a model that can be used by other colleges and universities for building long-term partnerships with schools to improve CS education. Important components of this model include summer and school year professional development, curriculum and support for four CS courses, a dual-enrollment program, teacher CS certification pathways, and a professional learning community. We offer suggestions and identify opportunities and challenges for those interested in developing a similar program.

We present a new high school level computer science (CS) curriculum that is a key component of a comprehensive college/high school partnerships program supporting secondary CS education in New York State. The year-long curriculum offers a broad introduction to CS and is designed using best practices for promoting diversity, equity, and inclusion. It was collaboratively designed and implemented by a team of college CS faculty and high school CS teachers participating in a research-practice partnership. This year (AY2023-2024) the curriculum is being taught in 27 school districts representing high-needs, rural, and suburban communities. Preliminary analysis of student data is included.

Previous research on belonging in computer science offers insights into the role that stereotypes play in reducing females' sense of belonging or fit in computer science (CS), which has been associated with their significant underrepresentation in the field. Drawing upon mixed methods (surveys and interviews), this study explores the quantitative variables associated with a sense of belonging for females in high school CS courses and provides qualitative insights from students to help explain why these factors matter. Pre/post survey analysis indicates that the courses are contributing to reducing pre-course gender gaps in students' perceived efficacy and belonging in a CS classroom. The surveys also suggest that females were more engaged and developed stronger relationships with teachers. And yet, females' commitments to continuing with CS had no statistically significant changes. Student interviews provide important context regarding the quantitative findings and describe how positive relationships with a female teacher, collaborative work and inclusive teaching practices played key roles in promoting a classroom sense of belonging for females. Overall, these results suggest that an academically engaging and socioemotionally supportive experience in a computer science course can reduce gender gaps and foster females' sense of belonging in the classroom even if they retain some reservations over their long-term fit in the field. The findings contribute to a more nuanced understanding of the factors that promote equitable experiences for females in CS and the relationship between classroom level belonging and long-term fit in computer science.

Expanding access to and engaging diverse groups of students in high school computer science (CS) classes depends on qualified CS teachers. In this paper, we describe how faculty at our liberal arts college built CS teacher capacity at over 20 school districts through comprehensive college/high school partnerships. The majority of these districts serve rural or high-needs students, groups underrepresented in CS classrooms. The program works primarily with in-service teachers from other disciplines, helping them develop the expertise to teach CS. It is comprehensive in that it includes curricula and professional development for a high school level CS course and a dual-enrollment college level CS course, pathways to CS certification, community events, and opportunities for teacher leadership and collaboration. These modes of engagement are structured so that novice and veteran teachers and college faculty have opportunities to interact in different capacities over several years to create a robust professional learning community. Initial survey results show increasing levels of teacher confidence and sense of belonging, and increasing student confidence in their CS abilities.

We present the first universal reconfiguration algorithm for transforming a modular robot between any two facet-connected square-grid configurations using pivot moves. More precisely, we show that five extra “helper” modules (“musketeers”) suffice to reconfigure the remaining n modules between any two given configurations. Our algorithm uses $$O(n^2)$$ pivot moves, which is worst-case optimal. Previous reconfiguration algorithms either require less restrictive “sliding” moves, do not preserve facet-connectivity, or for the setting we consider, could only handle a small subset of configurations defined by a local forbidden pattern. Configurations with the forbidden pattern do have disconnected reconfiguration graphs (discrete configuration spaces), and indeed we show that they can have an exponential number of connected components. But forbidding the local pattern throughout the configuration is far from necessary, as we show that just a constant number of added modules (placed to be freely reconfigurable) suffice for universal reconfigurability. We also classify three different models of natural pivot moves that preserve facet-connectivity, and show separations between these models.

In this paper, we describe our experiences with a new model for in-service computer science (CS) professional development that embeds college/university faculty into local high school classrooms partnered with a high school teacher. The high schools we have worked with had not previously offered any rigorous CS courses, and the teachers had little or no CS background. Our goal is to provide the development necessary for the high school teachers to be able to independently teach an engaging and rigorous college level CS course. We have leveraged the local nature of our program to ensure an on-going partnership between the high schools and the college/university lasting beyond the structured professional development program. Here we describe our program, the teachers and schools we have worked with, our community building efforts, and our next steps. We also present outcomes and data from our initial evaluations.

Recruiting and retaining STEM majors has been an ongoing challenge for colleges and universities. This research paper describes two initiatives to recruit and retain Computer Science (CS) majors that were implemented at Siena College starting in the fall of 2014. Both initiatives are directed at rising sophomores who have completed the first year CS sequence as an early strategy to encourage them to declare and complete the CS major. The first initiative is an early internship program directed at providing students an opportunity to apply those technical skills, extend their skill set, and introduce them to meaningful real-world projects between their freshman and sophomore years. The second initiative is a lab/classroom assistant program where sophomore or older students provide mentoring during lecture and lab sessions for the introductory CS courses. The paper provides preliminary findings, lessons learned, and directions for the future.

Computer Science (CS) is not taught in enough high schools thus many students arrive at college or university knowing little about it and often do not consider taking a CS course during their first year. At the same time, we encounter many college or university juniors and seniors who, while taking their first CS course, discover an aptitude and interest, at which point it is too late. We describe an innovative one-week residential summer program designed to educate non-computer science majors, before their second year of college or university, about the field's many areas and long-term prospects. The program has succeeded at encouraging undecided students to major or minor in CS and thus somewhat ameliorates the lack of CS in K-12 education and furthers the conference goal of "CS For All".

We describe a new methods of teaching computer science (CS) course tailored for mathematics education majors but also applicable to others interested in teaching CS. Goals of the course are enhancing their ability and confidence in developing and offering CS courses at high schools and starting CS courses at high schools that do not offer them. The course involves a combination of reading, programming, lesson/unit plan development, code reviews, and discussion of the various paradigms for introducing CS at the secondary level. Results indicate the course enhances the students' confidence, ability, and preparation for teaching CS in high schools.

We introduce the study of forcing sets in mathematical origami. The origami material folds flat along straight line segments called creases, each of which is assigned a folding direction of mountain or valley. A subset F of creases is forcing if the global folding mountain/valley assignment can be deduced from its restriction to F. In this paper we focus on one particular class of foldable patterns called Miura-ori, which divide the plane into congruent parallelograms using horizontal lines and zigzag vertical lines. We develop efficient algorithms for constructing a minimum forcing set of a Miura-ori map, and for deciding whether a given set of creases is forcing or not. We also provide tight bounds on the size of a forcing set, establishing that the standard mountain-valley assignment for the Miura-ori is the one that requires the most creases in its forcing sets. Additionally, given a partial mountain/valley assignment to a subset of creases of a Miura-ori map, we determine whether the assignment domain can be extended to a locally flat-foldable pattern on all the creases. At the heart of our results is a novel correspondence between flat-foldable Miura-ori maps and 3-colorings of grid graphs.

We introduce the problem of shape replication in the Wang tile self-assembly model. Given an input shape, we consider the problem of designing a self-assembly system which will replicate that shape into either a specific number of copies, or an unbounded number of copies. Motivated by practical DNA implementations of Wang tiles, we consider a model in which tiles consisting of DNA or RNA can be dynamically added in a sequence of stages. We further permit the addition of RNase enzymes capable of disintegrating RNA tiles. Under this model, we show that arbitrary genus-0 shapes can be replicated infinitely many times using only O(1) distinct tile types and O(1) stages. Further, we show how to replicate precisely n copies of a shape using O(log n) stages and O(1) tile types.

In this paper we show how an engaging problem can be used in both a discrete mathematics course and a programming course as a way to expose students to multiple methods of inquiry and to strengthen the links between the two courses. Since students typically take Discrete Mathematics and a programming course simultaneously, this is an opportunity for them to analyze a problem from multiple perspectives during a single semester. We describe how we have accomplished this using a relatively new problem that is easily stated and has a surprising solution that defies intuition. In the programming course, students experienced a design/empirical approach to the problem by implementing simulations of various solutions and collecting experimental results. By adjusting the emphasis of the programming assignment, we show that it can fit naturally into a range of programming courses, i.e. courses on introductory programming, data structures, and object-oriented techniques. In the Discrete Mathematics course, students analyzed solutions using tools from counting, probability, and calculus. We observed that by linking the two courses using a common problem, our students were more cognizant of inquiry methods and student engagement increased.

We show that the space of polygonizations of a fixed planar point set $S$ of $n$ points is connected by $O(n^2)$ ``moves'' between simple polygons. Each move is composed of a sequence of atomic moves called ``stretches'' and ``twangs''. These atomic moves walk between weakly simple ``polygonal wraps'' of $S$. These moves show promise to serve as a basis for generating random polygons.

We develop and prove correct an algorithm that enables active contours to correctly represent regions that undergo topology changes as the contours evolve. Using the incremental motion typical of active contours, we introduce the concept of motion regions to determine the new topology. When the topology changes (e.g. by contours intersecting), the motion regions are used to delete and and reconnect the contours to accurately describe the new region. Contour intersections can also occur without topology changes. These are also appropriately handled. The algorithm to perform this task is proved correct in a general framework that makes few assumptions about the contour representation. We describe how this algorithm is applied to a polygonal representation of the contours, and argue that it does not significantly affect execution time. Finally, this polygonal implementation is used in surface extraction and phytoplankton classification.