Principal Analog Mixed Signal ASIC Layout Engineer GCR Professional ServicesPrincipal Analog Mixed Signal ASIC Layout EngineerCambridge, MassachusettsRemoteContractorA successful candidate will assist ASIC development through creating custom analog layouts, floor planning entire chips, high level problem solving, and executing tape outs. ¿ Perform or guide physical layout, including floor-planning, and simulate circuits using extracted parasitic, contribute to design-for-test development.
NewPrincipal Digital Signal Processing Systems Engineer GCR Professional ServicesPrincipal Digital Signal Processing Systems EngineerCambridge, MassachusettsContractorAs Principal Signal Processing System Engineer you will work directly with customers and program managers to create innovative, multidisciplinary technical solutions, for a broad range of highly-complicated mission needs. You will have hands-on engagement with prototype development, which may include software or firmware coding, test equipment operation and programming, integration and validation, and field tests and customer demonstrations.
NewPrincipal Microwave Engineer Vaco LLCPrincipal Microwave EngineerBurlington, MA$180,000–$230,000 / yearDetermining compensation for this role (and others) at Vaco by Highspring depends upon a wide array of factors including but not limited to: the individual’s skill sets, experience and training; licensure and certification requirements; office location and other geographic considerations; other business and organizational needs. Determining compensation for this role (and others) at Vaco/Highspring depends upon a wide array of factors including but not limited to the individual’s skill sets, experience and training, licensure and certifications, office location and other geographic considerations, as well as other business and organizational needs.
Systems Engineer, Principal - TS DCS CorporationSystems Engineer, Principal - TSBedford, MA$123,639–$194,000 / yearC3BM’s main efforts are Architecture and Systems Engineering (ASE), Operational Response Team (ORT), and multiple mission integration teams such as Air, Maritime, and multiple acquisitions consisting of both the Advanced Battle Management System (ABMS) and Space. The MIT is responsible for translating operational requirements into technical solutions, developing integrated architecture, assessing risks, supporting acquisition execution strategies, and coordinating test and evaluation activities to ensure capabilities are delivered to operational users.
NewPrincipal Customer Solutions Architect, Ads Regulatory Compliance MicrosoftPrincipal Customer Solutions Architect, Ads Regulatory ComplianceBoston, MA$142,800–$274,800 / yearAs the Principal Customer Solutions Architect, Ads Regulatory Compliance, you will operate at the intersection of product, engineering, policy, legal, operations, and business strategy to translate emerging regulatory requirements into scalable frameworks, governance models, and solution architectures. There is a different range applicable to specific work locations, within the San Francisco Bay area and New York City metropolitan area, and the base pay range for this role in those locations is USD $188,000 - $304,200 per year.
NewPrincipal AI Software Engineer GE VernovaPrincipal AI Software EngineerEast Cambridge, MA$145,400–$242,500GE Vernova Inc. or its affiliates (collectively or individually, “GE Vernova”) sponsor certain employee benefit plans or programs GE Vernova reserves the right to terminate, amend, suspend, replace, or modify its benefit plans and programs at any time and for any reason, in its sole discretion. 10+ years of programming experience in a relevant language using modern front-end frameworks (React, Vue, or Angular) and multiple backend languages (Python preferred, Java, Node.js or Go).
NewPrincipal Front-Office Engineer AxelonPrincipal Front-Office EngineerBoston, MAAs a Principal Front-Office Engineer, you will serve as the technical lead embedded within the Risk team, driving design and implementation of small-scale applications and proof of concepts that will improve risk analysis, develop AI-enabled workflows, and enhance reporting systems & processes. Strong SQL skills required with a familiarity of financial data platforms (such as Bloomberg, FactSet, Aladdin, eFront, Moodys), financial databases, and data manipulation techniques preferred.
NewAssistant Principal of Holten Richmond Middle School Danvers Public SchoolsAssistant Principal of Holten Richmond Middle SchoolDanvers, MAFull time benefited employees at the Danvers Public Schools are eligible for a comprehensive benefits package offered through the Town of Danvers. Click HERE for a highlight of these benefits.
NewAssistant Principal Norfolk Public SchoolsAssistant PrincipalNorfolk, MA$104,000–$115,000 / yearAssist in the effective supervision and evaluation of teachers and staff Assist in the preparation for monthly faculty meetings Assist in the responsibility for health, safety, and welfare of the children and staff within the school environment Implement and monitor Chapter 504 regulations Facilitate 504 meetings Assist in establishing the master schedule for staff Participate in the district's administrative team meetings Build positive relationships with students, families, and staff members Make sound decisions under pressure, maintain confidentiality and exercise professional judgment Promote an inclusive, equitable, and positive school culture Conduct other staff duties and responsibilities as directed by the principal, or the Superintendent of Schools, including administering the school in the absence of the building principal. Norfolk Elementary Schools Norfolk, MA Title: Assistant Principal Location: Freeman-Kennedy School (Grades 3-6) Summary: The Assistant Principal assists the Building Principal in the overall leadership, administration, and daily operations of the school.
NewAdministrative Assistant to the Assistant Principal Minuteman Regional Vocational Technical School DistrictAdministrative Assistant to the Assistant PrincipalLexington, MA$43,000–$54,000 / yearAdditional Requirements: This position includes but is not limited to: walking around the school, observing students while they work in their program areas, standing for periods, occasionally lifting and carrying items up to 50 pounds, reading documents, using a computer, listening and speaking, using office equipment, maintaining energy throughout the day, and handling stress effectively. Proficient skills with Microsoft 365 (including Word, Excel, and Outlook); familiarity with district software platforms such as: Aspen preferred.
Middle School Assistant Principal Melrose Public SchoolsMiddle School Assistant PrincipalMelrose, MA$109,080.60–$117,028.52 / yearCarries out supervisory responsibilities in accordance with the organization's policies and applicable laws, including interviewing, hiring, and training employees; planning, assigning, and directing work; appraising performance; rewarding and disciplining employees; addressing complaints and resolving problems. Job Goal:Work closely with Middle School Principal, Assistant Principal, Superintendent, Superintendent Designee, Central Administration Team, Directors, and staff to create a safe, supportive, and responsive school environment.
NewAssistant Principal- Elementary School Weymouth Public SchoolsAssistant Principal- Elementary SchoolWeymouth, MAThe Assistant Principal ensures effective day-to-day implementation of programs aligned with the school's mission and supports the delivery of academic, social-emotional, and behavioral interventions within a Multi-Tiered System of Supports (MTSS) framework. We educate over 5,600 students in 11 school buildings, including Weymouth Early Childhood Center, eight elementary schools (grades K-5), Chapman Middle School (grades 6-8), and Weymouth High School (Grades 9-12).
26-27 Assistant Principal - PK-8 Somerville Public Schools26-27 Assistant Principal - PK-8Somerville, MAThe Assistant Principal serves as an instructional leader and key member of the school leadership team, supporting the Principal in fostering a high-quality, equitable, and inclusive learning environment. Support the Principal in providing instructional leadership, including supervising curriculum implementation and promoting high-quality teaching and learning practices.
26-27 Anticipated Assistant Principal, PK-8 Somerville Public Schools26-27 Anticipated Assistant Principal, PK-8Somerville, MAThe Assistant Principal serves as an instructional leader and key member of the school leadership team, supporting the Principal in fostering a high-quality, equitable, and inclusive learning environment. Support the Principal in providing instructional leadership, including supervising curriculum implementation and promoting high-quality teaching and learning practices.
Elementary Assistant Principal (Non-Teaching): Snug Harbor Community School Quincy Public SchoolElementary Assistant Principal (Non-Teaching): Snug Harbor Community SchoolQuincy, MAMaintains an inventory of school supplies, furniture, equipment, and books, and determines the needs of each of these areas for the purpose of preparing the annual budget. GENERAL DUTIES: The Assistant Principal will help plan, organize, administer, manage and coordinate all educational programs as assigned by the Principal.
Elementary Assistant Principal -Roosevelt Melrose Public SchoolsElementary Assistant Principal -RooseveltMelrose, MA$109,080.60–$117,028.52 / yearAssists in coordinating transportation, custodial, cafeteria and other support services for the purpose of ensuring the effective and efficient operation of the school site for quality delivery of services to students and staff. Reports to: Building Principal Job Goal: Work closely with the School Principal, Central Administration Team, Superintendent Designee, and staff to create a safe, supportive, and responsive school environment.
NewASSISTANT PRINCIPAL - SY 26-27 Lawrence Public SchoolsASSISTANT PRINCIPAL - SY 26-27Lawrence, MA$119,944–$132,033 / yearThe Assistant Principal serves as a key member of the school's leadership team, working under the direction of the Assistant Principal to advance a shared vision for high academic achievement, equitable practices, and a positive, inclusive culture. The Assistant Principal supports curriculum and instruction, talent management, student culture, family engagement, and operational systems to ensure a safe, welcoming, and high-performing learning environment for a diverse student population.
ASSISTANT PRINCIPAL - GRADE 11-13 Lawrence Public SchoolsASSISTANT PRINCIPAL - GRADE 11-13Lawrence, MA$119,944–$132,033 / yearThe Assistant Principal serves as a key member of the school's leadership team, working under the direction of the Assistant Principal to advance a shared vision for high academic achievement, equitable practices, and a positive, inclusive culture. The Assistant Principal supports curriculum and instruction, talent management, student culture, family engagement, and operational systems to ensure a safe, welcoming, and high-performing learning environment for a diverse student population.
Interim Assistant Principal, 2026-2027 school year, Concord Middle School Concord-Carlisle Regional School DistrictInterim Assistant Principal, 2026-2027 school year, Concord Middle SchoolConcord, MA$140,000–$155,000 / yearAssist in the implementation and monitoring of school curriculum to ensure that content, scope and sequence are appropriate to student learning at different grade levels and reflect the principles of the state's Common Core of Learning and Curriculum Frameworks. The Interim Assistant Principal will provide instructional, operational, and organizational leadership to the Concord Middle School community and the Concord Public Schools under the direction of the Superintendent of Schools and the Principal of Concord Middle School.
Waltham High School Assistant Principal of Teaching and Learning Waltham Public SchoolsWaltham High School Assistant Principal of Teaching and LearningWaltham, MAPhysical and Working Conditions: Must have the ability to sit for extended periods of time in a busy office environment; exhibit manual dexterity to enter data into a computer terminal; to see and read a computer screen and printed material with or without vision aids; hear and understand speech at normal levels and on the telephone; speak in audible tones so that others may understand clearly in person and on the telephone; ability to understand and follow oral and written instructions; physical agility to lift up to 25 pounds. MPDE is a collaborative of public school districts with a 40-year uninterrupted history committed to supporting the interest of its members to increase the numbers of teachers of color for their schools by providing recruitment support and related services.
Assistant Principal for the JFK Elementary School RANDOLPH PUBLIC SCHOOL DISTRICTAssistant Principal for the JFK Elementary SchoolRandolph, MAWork collaboratively with team chairs, Principal, central offices and families to ensure that provisions for Individual Education Programs, Progress Reports, ML processes & policies and transition plans are done in a timely and effective manner that enhances student academic, personal, social and emotional success. Be responsive to the needs and interests of all students while working in collaboration with the school principal to meet students where they are and to provide explicit support to ensure that students reach their full potential.
Middle/High School Assistant Principal Rockport Public SchoolsMiddle/High School Assistant PrincipalRockport, MAThe Assistant Principal collaborates with and supports the Principal in working directly with students and staff to maximize their potential by serving as an instructional leader, supervising and evaluating staff, and providing oversight of daily operations of the school by employing effective and efficient student-centered practices. The Rockport Public School District serves approximately 650 PreK-12th grade students on a two-building campus located in the picturesque coastal community of Rockport, MA which is 40 miles northeast of Boston at the tip of Cape Ann.
Assistant Principal Nettle Middle School Haverhill Public SchoolsAssistant Principal Nettle Middle SchoolHaverhill, MAWorks the requisite hours needed to meet the responsibilities of the aforementioned job description and be responsible for other instructional and general duties as indicated by the directives of the Superintendent of Schools or his/her designee, and policies of the Haverhill School Committee. Works with building administrators to affect an optimum learning climate for all students that promotes positive student interactions, learning, and quality curriculum.
NewAssistant Principal for Special Education (Randolph Community Middle School) RANDOLPH PUBLIC SCHOOL DISTRICTAssistant Principal for Special Education (Randolph Community Middle School)Randolph, MAWork collaboratively with the building principal, central offices and parents to ensure that provisions for Individual Education Plans, Progress Reports, and transition plans are done in a timely and effective manner that enhances student academic, personal, social and emotional success. Work collaboratively with the building principal and the central offices to ensure that all special education responsibilities such as: initial, annual and re-evaluation meetings are conducted and supported to ensure student centered learning and services.
Assistant Principal of Curriculum & Instruction, Grades 9-12, CRLS Cambridge Public SchoolsAssistant Principal of Curriculum & Instruction, Grades 9-12, CRLSCambridge, MAThe Opportunity: The Assistant Principal of Curriculum & Instruction will report directly to the Principal and will work cooperatively with the Assistant Principal of Student Affairs, Deans of Curriculum, and Deans of Students to build a positive, effective school-wide climate and to develop and support student activities within a comprehensive program that enhances student engagement and achievement, thus helping all students meet Cambridge Rindge and Latin School academic, social, and civic learning expectations. Key Responsibilities: Instructional Leadership: Provide instructional leadership centered on advancing educational equity, achieving instructional excellence, and closing identified opportunity gaps, fully aligned with the Cambridge Public Schools strategic plan, the CRLS School Improvement Plan, and the Massachusetts Curriculum Frameworks.
1.0 Assistant Principal PENTUCKET REGIONAL SCHOOL DISTRICT1.0 Assistant PrincipalGroveland, MAProvide feedback during coaching on teaching effectiveness and fidelity to guidance as provided by the teacher''s guide including concrete suggestions for improvements, especially related to strategies for working with struggling students, English language learners, and others with special needs within the regular classroom. These functions may include: District curriculum/program leadership and school-wide programming relative to assessment, curriculum development, special education, instructional practices, staff development, parent communication, scheduling, main office management, school discipline and safety, student transportation and facilities oversight.
Admin - Assistant Principal (COA) (SY24-25) Chelsea Public SchoolsAdmin - Assistant Principal (COA) (SY24-25)Chelsea, MAThe Assistant Principal is responsible for contributing a clear vision for student success, ensuring high-quality teaching and learning, fostering a nurturing and culturally responsive environment, and maintaining the flexible systems that allow COA students to balance school, work, and family. COA was created in partnership with Chelsea students, families, and community members, resulting in an innovative, flexible learning model that enables students to re-engage in school and earn a high-quality diploma on timelines that work for them.
Willard Assistant Principal Concord-Carlisle Regional School DistrictWillard Assistant PrincipalConcord, MA$135,000–$145,000 / yearThe Assistant Principal reports directly to the Principal and works collaboratively with the school leadership team, faculty, staff, and the broader school community to create an environment that values excellence, nurtures engagement, and fosters innovation. The Assistant Principal at Willard Elementary School plays a critical leadership role in fostering a positive, inclusive and high-performing school culture that emphasizes belonging for all students.
Assistant Principal Interim Belmont Public SchoolsAssistant Principal InterimBelmont, MAQUALIFICATIONS: Master's degree, MA Principal/Assistant Principal Certification or eligibility, school teaching experience. Benefits-eligible based on the terms and conditions set forth by Town of Belmont.
NewAdministrative Assistant to the Middle School Principal Watertown Public SchoolsAdministrative Assistant to the Middle School PrincipalWatertown, MAPhysical Demands: Regularly required to sit, stand, walk, talk, hear, operate a computer, hand-held learning devices and other office equipment, reach with hands and arms, and must occasionally lift and/or move up to 10 pounds. Maintains general levels of support for other office personnel in the assigned area when there are short-term absences or persons are away from their desks.
Administrative Assistant to the Principal Winchester Public SchoolsAdministrative Assistant to the PrincipalWinchester, MACollects money from students/teachers, counts money and adds to a deposit sheet, deposits funds into our school bank account, records deposits on Student Activities workbook and submits all necessary deposit paperwork to the Central Office. Handles all withdrawals and incoming students during the summer when the registrar/database coordinator is out, including checking the new student registration tab on Aspen daily, printing out and compiling new student files.
Assistant Principal - High School (26-27 school year) San Angelo Independent School DistrictAssistant Principal - High School (26-27 school year)MAAssistant Principal - High School (26-27 school year) - San Angelo Independent School District.
Elementary Assistant Principal Andover Public SchoolsElementary Assistant PrincipalMAAndover Public Schools (APS) seeks candidates who embody our ethos, which includes valuing the identities of all students, high expectations for all students, teaching excellence, collaboration, innovation, respect, and responsibility. Demonstrate knowledge of current elementary curricula (Readers Workshop, Writers Workshop, Math In Focus, Fountas and Pinnell Classroom, Foss Science) and instructional techniques.
Assistant Principal for Special Education (2026-27 SY) NEWTON PUBLIC SCHOOL DISTRICTAssistant Principal for Special Education (2026-27 SY)Newton, MASUMMARY: The Assistant Principal for Student Services provides special education and guidance leadership, including oversight of staff and programming at the middle school. Monitor and encourage the development of new programs designed to meet the needs of students with special needs in the least restrictive environment.
NewPrincipal (Lunch) Aide Westford Public SchoolsPrincipal (Lunch) AideWestford, MAThe Principal Aide supervises students during lunch, including transitioning students from their classrooms to the cafeteria, circulating around the cafeteria while eating, and dismissing students to their classrooms at the end of the lunch period. Manage Lunch Fund Procedure (File Lunch Fund Cards/Send Out Lunch Fund Forms).
Principal Aide Westford Public SchoolsPrincipal AideWestford, MA5.Manage Lunch Fund Procedure (File Lunch Fund Cards/Send Out Lunch Fund Forms) 6.Assure Epipen/Diabetic bags go to playground and back to classroom with students after the Recess/Lunch period. The Principal Aide supervises students during lunch, including transitioning students from their classrooms to the cafeteria, circulating around the cafeteria while eating, and dismissing students to their classrooms at the end of the lunch period.
Assistant Superintendent/Principal Greater Lowell Technical High SchoolAssistant Superintendent/PrincipalMAOversees schedules and procedures regarding assignments for school activities, instructional activities, student and faculty meetings, extra-curricular activities, safety program, athletics, teacher monitoring duties, student publications, and student fund-raising. OTHER INFORMATION: The statements contained herein reflect general details as necessary to describe the principal functions of this position, the level of knowledge and skill typically required, and the scope of responsibility, but should not be considered an all-inclusive listing of requirements associated with the position.
Assistant Principal / Special Education Administrator Gloucester Public SchoolsAssistant Principal / Special Education AdministratorGloucester, MAThe ideal candidate will be a passionate advocate for students with disabilities, possess strong leadership and organizational skills, and be committed to creating an inclusive and equitable learning environment for all. Job Description: West Parish Elementary School is seeking an Elementary Special Education Administrator/Assistant Principal to join our team.
Assistant Principal Stoughton Public SchoolsAssistant PrincipalStoughton, MASalary for this position is listed in the Unit B Bargaining Agreement Salary Grid: https://files-backend.assets.thrillshare.com/documents/asset/uploaded_file/2153/Stoughton/6b49b99c-b794-4aeb-b2f1-47c38dfa547a/Stoughton_Teachers_Association_Contract_-_Unit.pdf?disposition=inline . Stoughton High School has an opening for an Assistant Principal.
NewVice Principal (Bilingual Spanish Preferred) Framingham Public SchoolsVice Principal (Bilingual Spanish Preferred)Framingham, MAThe requirements listed below represent the knowledge, skills, and abilities required: Communication: Strong oral and written communication skills; ability to present information clearly and respond effectively to questions from district staff, school administrators, the School Committee, and the broader community. Leadership Experience: At least three (3) years of demonstrated experience in a leadership capacity, such as teacher leadership, leading professional learning opportunities, or active involvement in school/district visioning and strategic improvement planning.
NewAdministrative Assistant to the Principals (School Year) Mendon Upton Regional School DistrictAdministrative Assistant to the Principals (School Year)Upton, MAJob Qualifications/Skills Needed: Excellent organizational and communication skills; Working knowledge of office procedures and operation of common office equipment; Excellent verbal and written communication skills; Highly organized and extremely detail-oriented; Ability to maintain complete confidentiality and discretion in dealing with classified information; Ability to use tact, diplomacy, and judgment when working with a variety of constituencies; Positive attitude and a willingness to help others; Strong problem-solving skills; Flexible and able to change priorities quickly; Excellent computer skills (Google Workplace, Drive, PowerSchool, Canva). The ideal candidate will embrace our district''s values and priorities, fostering a supportive and inclusive classroom environment where all students feel valued, respected, and challenged to achieve their highest potential.
Assistant Principal Elementary Pool 26-27 SY Sharyland Independent School DistrictAssistant Principal Elementary Pool 26-27 SYMATeaching jobs, educator jobs, school jobs | SchoolSpringYou need to enable JavaScript to run this app.
Temporary - Principal Clerk (WSTA) (SY26-27) Chelsea Public SchoolsTemporary - Principal Clerk (WSTA) (SY26-27)Chelsea, MAThe school system educates over 6,300 students in 11 schools, including a pre-K-1st grade school, 4 elementary schools, 3 middle schools, 2 high schools, and 1 virtual school. Maintains records pertaining to students, compiles statistical reports, requisition's supplies and materials, processes invoices for payment, maintains appropriate financial accounts, etc.
Development Assistant - Principal and Major Gifts Boston Children's HospitalDevelopment Assistant - Principal and Major GiftsBoston, MA$19.06–$27.64 / hourJob/Department Summary: Working closely with the Principal & Major Gifts team, the Development Assistant will support operational excellence and advance regional fundraising initiatives. Prepare invoices for the department including payment requisitions for vendors, employee reimbursements and serves as contact to resolve discrepancies.
Principal Bookkeeper, Accounts Payable Town of DuxburyPrincipal Bookkeeper, Accounts PayableDuxbury, MA$25.48–$34.39 / hourPerforms similar or related work as required, directed, or a situation dictates and other special projects, including research, analysis, data collection, and reporting on special projects as needed by the Town Accountant or Finance Director. Nature of Work: The Principal Bookkeeper prepares professional financial records, advanced bookkeeping, complex computer application work, and clerical work products; primary work tasks relate to accounts payable, accounts receivable, and general administration.
Principal Software Engineer - AI New Balance, IncPrincipal Software Engineer - AIMA$120,000–$150,000 / yearA core focus of this role is designing and building enterprise-grade AI assistants and automations using RAG and agentic AI techniques -software agents that can plan, coordinate tools, interact with systems, and execute multi-step workflows with appropriate guardrails. This team is responsible for researching and delivering AI based solutions across the company to improve internal workflows, decision-making, and operational efficiency across a wide range of business functions, including operations, supply chain, finance, product, and corporate services.
Principal Software Engineer - AI New BalancePrincipal Software Engineer - AIBrighton, MA$120,000–$150,000 / yearA core focus of this role is designing and building enterprise-grade AI assistants and automations using RAG and agentic AI techniques -software agents that can plan, coordinate tools, interact with systems, and execute multi-step workflows with appropriate guardrails. This team is responsible for researching and delivering AI based solutions across the company to improve internal workflows, decision-making, and operational efficiency across a wide range of business functions, including operations, supply chain, finance, product, and corporate services.
Principal Technician - ASIC Infineon Technologies AGPrincipal Technician - ASICMAEmployment at Infineon is contingent upon proof of your legal right to work in the United States under applicable law, verification of satisfactory references and successful completion of a background check and drug test, and signing all your on-boarding documents. As a global leader in semiconductor solutions in power systems and IoT, Infineon enables game-changing solutions for green and efficient energy, clean and safe mobility, as well as smart and secure IoT.
Mergers & Acquisition, Lead Transaction Principal Teradyne, Inc.Mergers & Acquisition, Lead Transaction PrincipalNorth Reading, MA$219,900–$351,900 / yearTeradyne is a global leader in automated test equipment and industrial automation, enabling customers across the semiconductor, electronics, and advanced manufacturing ecosystem to accelerate innovation and deliver high-quality products at scale. Across semiconductor test, system-level and wafer-level test, photonics, and adjacent semiconductor capital equipment, Teradyne operates at the intersection of deep engineering, complex supply chains, and long investment cycles.
Investment Principal, Public Markets Partner's CapitalInvestment Principal, Public MarketsBoston, Massachusetts$160,000–$220,000 / yearClients include Syracuse University, Sesame Workshop, INSEAD Business School, New York’s Metropolitan Opera, San Francisco Symphony, Eton College, Colorado College, several Oxford and Cambridge University Colleges, several family offices around the world, and senior executives from leading global investment firms. With $75B+ in assets under management, the firm constructs customized investment portfolios for its clients tapping into its deep network of partnerships with what we consider exceptional asset managers across all major asset classes.