CS2Mulch: Physical Manipulatives for Teaching Advanced Data Structures

The organization of stacks and queues are often familiar to students because they have previously stacked plates and have stood in many lines. However, it is less frequent for them to have an innate mental model of higher-level tree and hash-based data structures. This demo will highlight the CS2Mulch project, which provides engaging manipulatives for demonstrating concepts in advanced data structures to build these mental models. Instructors can use these tools to support lessons on sorting algorithms, binary search trees, heaps, sets, and hash tables. Two original decks of cards form the basis for interactive classroom games and collaborative peer exercises in CS2. The Acorns deck consists of cards numbered with integers 00-69. These cards can be overlapped on the corners to demonstrate insertion and removal algorithms for binary trees or heaps. The Menagerie deck consists of cards that display an animal, along with two integers computed by passing the name through two simple hash functions, Murmur3 and FNV, modulo 8. Additional cards are numbered 0 to 7, to be used as markers for arrays within hash table implementations. The CS2Mulch decks, along with lesson plans and supporting materials, are freely available at https://mgoadric.github.io/cs2mulch/, either for PDF download, virtually through the online board game software Tabletopia, or for purchase through on-demand printing at The Game Crafter. This work is supported through a 2019 SIGCSE Special Project Grant.