In the Experimental Research Division, students use the scientific method to answer a question or solve a problem. This involves conducting background research, developing a hypothesis or proposed solution, designing and performing experiments, analyzing experimental data, and drawing conclusions based on the results. Research may be conducted in any area of Science, Technology, Engineering, or Mathematics (STEM).

By participating in the Experimental Research Division, students have the opportunity to discuss their scientific research with judges and receive valuable feedback.

The TNJSF offers a wide variety of cash prizes, awards, and advancement opportunities. The Grand Prize for the Experimental Research Division includes several all-expenses-paid trips to compete at the Regeneron International Science and Engineering Fair (ISEF), the world's largest international pre-college science competition.

Category judging takes place on Saturday afternoon. Each category is assigned a group of judges led by a Category Captain. Judges should arrive at the Judges’ Room at least 30 minutes before judging begins. They will receive project assignments from the Category Captain and instructions from the Judging Coordinators.

Each judge is assigned a maximum of eight projects. Judges then proceed to the exhibit area and have approximately 2½ hours to evaluate their assigned projects. During this time, judges meet individually with students at their project displays. Each project is evaluated by at least three judges, with only one judge interviewing a student at any given time.

After judging concludes, judges return to the Judges’ Room to discuss the projects and determine awards for First, Second, Third Place, and Honorable Mention. Deliberations typically last 30–60 minutes, depending on the size of the category.

Category judging follows a common standard across all categories using the TNJSF Judging Criteria. Projects are evaluated against an absolute standard rather than ranked solely against one another. As a result, multiple projects may receive the same placement, or a placement may be withheld if the judging committee determines that the required standard has not been met.

Special Awards judging takes place on Sunday morning. Each special award is assigned a team of judges led by a Captain. Judges should arrive at the Judges’ Room at least 45 minutes before judging begins to receive project assignments and instructions from the Judging Coordinators.

Judges then proceed to the exhibit area and have approximately two hours to evaluate their assigned projects. At least two judges on each award team should evaluate every project under consideration. Following judging, judges return to the Judges’ Room to determine award recipients. Deliberations typically last 30–60 minutes, depending on the number of projects being considered.

Special Awards range from discipline-specific awards, such as the Geoscience Award, to broader recognitions such as the Innovation Award. Because projects may qualify for multiple awards, they may be evaluated by different judging teams. For Special Awards only, judges may conduct interviews in groups of up to three judges.

On Saturday afternoon, Category Captains lead their judging teams in determining project placements within their assigned categories.

On Sunday, all Category Captains become members of the ISEF Panel, which selects the winners of the ISEF Grand Prize—an all-expenses-paid trip to compete at the annual Regeneron International Science and Engineering Fair (ISEF).

During the Sunday morning session, the ISEF Panel evaluates all projects that placed First in their categories. Captains work in pairs, consisting of one judge from the physical sciences and one from the biological sciences. At the conclusion of the morning session, the panel selects the projects that will advance to the final round of judging.

On Sunday afternoon, finalist projects relocate their displays to the designated judging area for a final 1 hour and 45 minute judging session, divided into six 15-minute interview blocks. Following the final interviews, the ISEF Panel selects the Grand Prize winners. At the panel's discretion, one team project may also receive an ISEF Grand Prize.

As a result, Category Captains participate in judging on Saturday afternoon, Sunday morning, and Sunday afternoon.

A Topic Presentation is an exploration of the current knowledge about a topic in any area of Science, Technology, Engineering, or Mathematics (STEM). Students can choose any topic within STEM that they are excited about.

Students conduct a literature search, narrow the focus of their topic, and compile information about existing scientific knowledge and the questions that are still being investigated. There is no experimentation, data collection, or use of models.

This program allows students to explore and dig deeper into a STEM area that has sparked their interest and imagination. By presenting their topic during a poster session at the in-person Fair, students have the opportunity to discuss their scientific interests with judges and receive feedback and encouragement to advance their work.

Judging of Topic Presentations takes place on Sunday morning. Each category is assigned a group of judges with a Lead Judge. Judges are asked to arrive at the Judges’ Room at least 30 minutes before the start of judging.

At that time, judges will receive instructions from the Judging Coordinators. Each judge will be assigned a maximum of nine projects. Judges then proceed to the exhibit area and have two hours to evaluate their assigned projects.

During the judging period, judges will meet with students at their posters to evaluate their work. Each project is judged by a minimum of three judges, with only one judge interviewing a student at any given time. Judging is not conducted in teams.

Students will orally present the information on their poster to each judge. Students will have approximately 10–12 minutes with each judge, including time for questions and answers.

At the end of the judging period, judges will reconvene in the Judges’ Room to discuss the projects and determine which projects will receive awards. Deliberations take approximately 30 minutes.

One winner will be selected from each Topic Presentation category. The Lead Judge for each category will report the results to the Judging Coordinators.