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ARC Core (Formerly Zoology One)

Essa Rating
No. Studies
No. Students
Average Effect Size

Program Description

Evaluated for Kindergarten, ARC Core is a K-12 curriculum that meets the literacy needs of students in English and Spanish in a variety of learning environments. Through extensive reading, writing, research, and analysis, students develop agency and expertise in a wide variety of disciplines. ARC Core includes knowledge-building units that integrate science content (e.g., Marine Life), social studies content (e.g., U.S. States), and literature content (e.g., Traditional Tales), while developing literacy skills and vocabulary. ARC Core provides four 9-week units per grade. Teachers receive a new set of topically aligned instructional materials and texts to use with each 9-week unit, but the structures and practices that guide instructional delivery are consistent throughout the year.

Program Outcomes

The efficacy of ARC Core (formerly Zoology One) was examined in a multi-site, randomized controlled study in 71 kindergarten classrooms across 21 schools in Philadelphia. Classrooms assigned to treatment were expected to implement ARC Core in place of regular literacy instruction for 120 minutes per day, for the full school year. Control classrooms continued to implement the district’s business-as-usual literacy program for 120 minutes per day. After one year, students in ARC Core classrooms performed significantly higher on the AIMSWeb Letter Naming Fluency and the WMRT Passage Comprehension compared to the control group (ES = +0.28 and +0.16 respectively), qualifying ARC Core for an ESSA “Strong” rating.

Staffing Requirements

ARC Core is implemented by classroom teachers to provide grade level instruction and supports during an integrated literacy block. No additional staff required.

Professional Development/Training

Certified Executive Coaches work side by side with teachers and leaders to establish a high-quality implementation of ARC Core across classrooms, use the science of improvement to refine implementation, nurture a culture of collaborative innovation, and scale refinements systemwide. Professional development is delivered in-person, via live virtual sessions, and asynchronous courses.


ARC offers a range of digital solutions to support ARC Core including a content delivery and performance management system, e-libraries, and educational games. ARC’s digital tools integrate with all Learning Management Systems (LMS) and support single sign on (SSO) with Clever Instant Login and ClassLink One Click Login. ARC’s digital materials can be accessed on any Internet-connected device with a web browser that supports HTML5, JavaScript, CSS, and cookies. ARCs digital tools are being used nationwide on Windows PCs, Macs, Chromebooks, iPads, iPhones, Android tablets, and Android phones.