What is ACSL?

The American Computer Science League (ACSL) is a computer science competition for school students. It challenges students to reason about algorithms, understand how programs work and apply fundamental computing concepts. 

Why participate?

ACSL suits students interested in computing, mathematics, logic and programming. Its four-round structure encourages sustained preparation rather than a single examination. Students considering computer science or related university courses can use their participation and accurately described achievements to demonstrate academic interests and learning. Participation or an award does not guarantee university admission.

Competition structure

The season consists of a qualifying Round 1 followed by Rounds 2–4. The top 65% of eligible teams and individuals in Round 1 progress to Rounds 2–4. Registration for a season does not guarantee progression: students who do not qualify cannot take the subsequent competitive rounds. Awards for Rounds 2–4 are determined after those rounds have been completed.

The published full session for coding divisions is 160 minutes, containing a 30-minute written test and a two-hour programming challenge. The precise programming start time and arrangements for the remaining ten minutes will be confirmed in the examination instructions. The Elementary division takes only the written test. 

Divisions and year levels

New Zealand year levels below are a guide based on the published grade ranges. PEC will confirm eligibility and the appropriate division before finalising entry.

Elementary — individual written contest

For students in Grades 3–6, approximately NZ Years 4–7. No programming task or team is required. Students solve computer science reasoning questions; prior coding experience is not essential. The written test lasts 30 minutes. The published Elementary specification lists six questions worth one point each, subject to the actual paper.

Junior — individual work with team scoring

For middle-school students, approximately NZ Years 8–10. Students beyond Grade 9 (approximately NZ Year 10) may not enter Junior. Each round includes a 30-minute written test and a two-hour programming challenge.

Intermediate — individual work with team scoring

For senior high-school students with programming experience and suitably experienced younger students. NZ Years 11–13 is a guide. Each round includes a 30-minute written test and a two-hour programming challenge.

Senior — individual work with team scoring

For high-school students with stronger programming experience, including students studying advanced computer science. NZ Years 11–13 is a guide. Each round includes a 30-minute written test and a two-hour programming challenge. Experienced younger students may choose a higher division when eligible; older students may not choose a lower division that excludes their grade.

Topics by round

Round 1

Elementary: computer number systems. Junior, Intermediate and Senior: computer number systems, recursive functions and program tracing with branches.

Round 2

Elementary: prefix, infix and postfix notation. Junior: expression notation, bit-string operations and program tracing with loops. Intermediate and Senior: expression notation, bit-string operations and LISP.

Round 3

Elementary: Boolean algebra. Junior: Boolean algebra, data structures and program tracing. Intermediate and Senior: Boolean algebra, data structures, finite-state automata and regular expressions.

Round 4

Elementary: graph theory. Junior: graph theory, digital electronics and program tracing. Intermediate and Senior: graph theory, digital electronics and assembly language. The final paper and examination instructions determine the precise topic coverage.

Awards and results

The published Rounds 2–4 award categories are assessed separately by division. Individual recognition includes Perfect Score (full marks in all three advanced rounds), Top Scores (top 20%) and Honorable Award (top 55%). Team categories include Gold (top 10%), Silver (top 25%), Bronze (top 35%) and Honorable Award (top 55%). These are published category thresholds, not an assurance that every entrant will receive an award.

PEC registration 

Round 1 registration deadline: Friday 27 November 2026.

Rounds 2–4 registration deadline: Friday 22 January 2027. 

Rounds 2–4 — for qualifying entrants

Round 2: Saturday 13 February 2027, 19:00–21:40 NZDT.

Round 3: Saturday 13 March 2027, 19:00–21:40 NZDT.

Round 4: Saturday 17 April 2027, 18:00–20:40 NZST.

Elementary takes only the first 30 minutes of each session. The top 65% of eligible teams and individuals from Round 1 qualify. Registration for the complete Rounds 2–4 package closes Friday 22 January 2027; all three rounds are paid together.