What Is Transitional Kindergarten? A Parent's Guide to TK in California

If your child is turning four, you have probably heard other parents mention “TK.” Transitional kindergarten is California’s free school year for four-year-olds, and it is now open to every child who meets the birthday cutoff. This guide explains what it is in plain English so you can decide whether it fits your family.

What Is Transitional Kindergarten (TK)?

Transitional kindergarten is the first year of a two-year kindergarten program in California public elementary schools. Children attend TK the year they are four, then move on to kindergarten the following year at age five.

TK is taught by a credentialed teacher on an elementary school campus. It uses a modified kindergarten curriculum built for four-year-olds, with plenty of play, hands-on learning and social-emotional growth alongside early literacy and math. California’s Preschool/Transitional Kindergarten Learning Foundations describe the skills children typically build in these years.

Who Is Eligible for TK?

Every child who turns four years old on or before September 1 of the school year is eligible for TK in a California public school. Children who are already five by September 1 enroll in kindergarten instead.

Some districts also allow early enrollment for children who turn four after September 1, if space allows. Policies vary, so ask your district directly.

What a TK Classroom Looks Like

State law sets a few guardrails that make TK different from a typical kindergarten class:

• Smaller groups. Districts must keep TK classes to an average of 24 students or fewer at each school.
• More adults. Starting in 2025–26, TK classrooms must average about one adult for every 10 students, usually a teacher plus an aide.
• Teachers trained in early childhood. Besides an elementary teaching credential, TK teachers need early childhood training, such as 24 units in early childhood education or child development, a Child Development Teacher Permit or comparable experience teaching preschool-age children.
• Learning through play. Expect centers, art, songs, stories, outdoor time and small-group activities more than worksheets.

A typical TK day includes arrival and circle time, small-group literacy and math activities, choice time at learning centers, outdoor play, lunch or snack, and a story or closing circle. Exact routines vary by school and teacher.

Is TK Free? Is It Required?

TK is free. It is part of the public school system and funded by the state, just like kindergarten. There is no tuition and no income requirement.

TK is also optional. You can choose TK, keep your child in preschool for another year or do a mix. In California, school attendance becomes required at age six.

TK Hours and Before and After Care

TK follows the elementary school day and calendar, so it ends in the early or mid afternoon and closes for school breaks and summer. Some schools run full-day TK and others part-day.

Many districts offer before and after school programs for TK through 6th grade students, including programs funded by California’s Expanded Learning Opportunities Program. Spaces and hours vary by school. Working parents often pair TK with one of these programs or with a licensed child care center for the hours school does not cover. Our guide to TK vs. preschool in Concord walks through the schedule gap and how families plan around it.

How TK Became Universal in California

California created transitional kindergarten through the Kindergarten Readiness Act of 2010. At first it served only children with fall birthdays who just missed the kindergarten cutoff.

Starting in 2022–23, the state widened eligibility every year by moving the birthday window back a few months at a time. By the 2025–26 school year, TK became universal: every child who turns four by September 1 now qualifies.

TK in Concord: Mt. Diablo Unified

Families in Concord enroll in TK through Mt. Diablo Unified School District (MDUSD). Eligibility follows the statewide September 1 cutoff. Before you enroll, ask your neighborhood school:

• Is TK full-day or part-day at this school?
• What time does TK start and end?
• Is there before and after school care on campus, and is there a waitlist?
• Does the district offer early enrollment if my child turns four after September 1?
• What documents do I need to register?

Still weighing TK against another year of preschool? Read our side-by-side TK vs. preschool guide for Concord families.

Where Super Kidz Club Fits

Super Kidz Club does not run TK; transitional kindergarten is a public-school program. We offer a Reggio-inspired preschool for ages 2 to 5 that builds the confidence, curiosity and early skills children carry into TK and kindergarten, plus a before and after school program for school-age children. If you are deciding when your child should start TK, or how to cover the hours around it, schedule a tour and we will talk it through with you.