5. Presenting to Judges

Presenting to Judges

A science fair presentation is your opportunity to explain the story of your investigation.

Your display board provides the visual information, but you provide the explanation. Judges want to understand what you investigated, why you chose the question, how you conducted the experiment, what your evidence showed, and what you learned.

You do not need to memorize a long speech or use complicated scientific vocabulary. A strong presentation shows that you understand your own investigation and can explain it clearly.

A useful goal is:

Know your project well enough that you can explain it naturally rather than simply reciting it.

What Are Judges Looking For?

Judges are usually interested in more than whether your experiment produced an impressive result.

They may want to know whether you understand:

• your research question
• the science behind the investigation
• your hypothesis
• your variables
• your experimental procedure
• your data
• patterns in your results
• limitations of the investigation
• your conclusion
• possible improvements

They may also want to see whether you can use evidence to support what you say.

If your results did not support your hypothesis, that does not make your investigation a failure.

Good science depends on evidence, not on getting the result you originally expected.

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Prepare a Short Project Summary

You should be able to summarize your entire project in a few minutes.

A useful structure is:

Question → Reason → Hypothesis → Method → Results → Conclusion → Evaluation

For example:

Question

"I investigated how water temperature affects the time required for sugar to dissolve."

Reason

"I chose this because temperature affects particle motion, and I wanted to investigate how that influences dissolving."

Hypothesis

"I predicted that sugar would dissolve faster at higher temperatures."

Method

"I tested five water temperatures. I used the same volume of water and mass of sugar for every trial and completed three trials at each temperature."

Results

"The dissolving time generally decreased as temperature increased."

Conclusion

"The results supported my hypothesis. Higher water temperatures were associated with shorter dissolving times."

Evaluation

"One limitation was keeping the stirring rate exactly constant. A mechanical stirring system could improve the investigation."

That provides the judge with the complete story without explaining every small detail.

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Start with the Research Question

Your research question provides a natural starting point.

Instead of beginning with:

"So, um, this is my project..."

you can begin directly:

"My investigation examined how the concentration of salt in water affects the germination of bean seeds."

The judge immediately knows what the project is about.

Then briefly explain why you chose the question.

For example:

"I was interested in this because salt can accumulate in soils, and I wanted to investigate whether increasing salinity would affect seed germination."

This connects the investigation to a larger scientific idea.

Explain the Science Behind the Project

Judges may ask about your background research.

You should understand the scientific ideas connected to your investigation.

For example, if your investigation concerns:

temperature and dissolving

you should understand ideas such as:

• particles
• kinetic energy
• solute
• solvent
• solution
• dissolving
• temperature

If your investigation concerns:

light and plant growth

you should understand ideas such as:

• photosynthesis
• light energy
• glucose
• chlorophyll
• limiting factors
• plant growth

You do not need to explain every scientific fact you researched. Focus on the science that helps the judge understand why your investigation makes sense.

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Explain Your Hypothesis

Tell the judge what you predicted and, more importantly, why.

Weak explanation:

"I thought the hotter water would work better."

Stronger explanation:

"I predicted that increasing water temperature would decrease dissolving time because particles have greater average kinetic energy at higher temperatures."

The second response shows scientific reasoning.

A hypothesis should connect:

prediction + scientific explanation

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Explain Your Variables

Be prepared to identify the variables in your investigation.

For example:

Research question: How does ramp height affect the time required for a toy car to travel 1.0 m?

Independent variable: Ramp height

Dependent variable: Travel time

Control variables:

• same car
• same ramp
• same surface
• same release point
• same travel distance
• same timing method

A judge might ask:

"Why did you keep the same car?"

A strong response would be:

"Different cars could have different masses, wheels, friction, or rolling resistance. Keeping the same car helped ensure that ramp height was the main variable being changed."

That demonstrates understanding of fair testing.

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Explain the Method Without Reading It

You do not usually need to read every numbered step from your display.

Instead, summarize the important parts.

For example:

"I tested five ramp heights from 10 cm to 50 cm. At each height, I released the same car from the same position and measured the time required to travel one metre. I repeated each condition three times and calculated the average."

This tells the judge:

• what was changed
• what was measured
• what was controlled
• how many trials were performed
• how the data were processed

That is usually much more useful than reading a long procedure aloud.

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Use Your Display as a Visual Aid

Your display board should support your presentation.

You can point to:

• your research question
• experimental photographs
• diagrams
• data tables
• graphs
• conclusion

For example:

"This photograph shows the experimental setup."

Then:

"This graph shows the main pattern in my results."

The board helps the judge follow your explanation.

However, avoid turning your back to the judge and reading directly from the display.

The board should support you, not replace you.

Focus on Your Results

Your results are one of the most important parts of the presentation.

Do not simply say:

"Here is my graph."

Explain what the graph shows.

For example:

"The graph shows that dissolving time generally decreased as water temperature increased. At the lowest temperature, the average dissolving time was greatest, while the highest temperature produced the shortest average dissolving time."

You are identifying a trend.

Depending on the investigation, you might discuss:

• increases
• decreases
• maximum values
• minimum values
• similarities
• differences
• relationships
• unusual results
• patterns

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Use Numbers When They Help

Scientific evidence becomes stronger when you refer to actual measurements.

Instead of:

"The plants with more light grew much more."

you might say:

"The plants receiving 12 hours of light per day had a greater average height than the plants receiving four hours per day."

If appropriate, include important numerical values.

For example:

"Average height increased from 8.4 cm in the four-hour treatment to 14.7 cm in the twelve-hour treatment."

You do not need to memorize every value in your data table.

Know the most important results.

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Evidence, Not Opinion

Judges may ask:

"Why do you think that?"

Your answer should refer to scientific evidence whenever possible.

For example:

Question: "Why did you conclude that increasing ramp height increased the car's speed?"

Weak answer:

"Because that's what I thought would happen."

Stronger answer:

"The average travel time decreased as ramp height increased. Since the car travelled the same distance in less time, its average speed increased."

The stronger answer uses the collected evidence and scientific reasoning.

A useful response structure is:

Claim → Evidence → Scientific reasoning

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Claim, Evidence, Reasoning

This structure can help you answer many questions.

Claim

State what you think the evidence shows.

Increasing water temperature decreased dissolving time.

Evidence

Refer to your results.

The higher-temperature trials consistently produced shorter average dissolving times.

Reasoning

Connect the evidence to scientific knowledge.

At higher temperatures, particles have greater average kinetic energy and move more rapidly, increasing interactions between the solvent and solute.

Together:

Claim + Evidence + Reasoning

creates a strong scientific explanation.

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Justify Your Conclusion

Your conclusion should answer the research question.

Suppose your question was:

How does salt concentration affect bean seed germination?

A useful conclusion might be:

"The percentage of seeds that germinated decreased as salt concentration increased. Therefore, under the conditions tested, higher salt concentrations reduced bean seed germination."

Notice the phrase:

"under the conditions tested"

Scientific conclusions should usually stay within the limits of the evidence.

You tested particular:

• concentrations
• seeds
• temperatures
• times
• conditions

Your experiment does not necessarily prove what happens under every possible condition.

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Avoid Overstating Your Results

Suppose you tested 30 bean seeds.

You should not conclude:

"Salt prevents all plants from growing."

That conclusion goes far beyond your evidence.

A more appropriate conclusion might be:

"Increasing salt concentration reduced the percentage germination of bean seeds under the conditions tested."

Good scientific communication distinguishes between:

what your evidence supports

and

what might be possible but has not been demonstrated.

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Be Ready to Discuss Anomalous Results

A judge may notice an unusual data point.

Do not try to hide it.

Suppose most of your measurements were:

22.1 s, 21.8 s, 22.4 s

but one was:

35.7 s

A judge might ask:

"Why is this value so different?"

You could answer:

"That result was anomalous compared with the repeated measurements. I cannot be certain why it occurred, but possible causes include a timing error or an inconsistency in the procedure. Additional trials would help determine whether it represented experimental error or real variation."

That is a scientifically responsible answer.

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It Is Fine to Say "I Don't Know"

Judges may ask a question you cannot answer.

Do not invent an explanation.

Instead, you might say:

"I don't know, but that would be interesting to investigate."

or:

"My data don't allow me to answer that question confidently."

or:

"I did not control that variable, so I can't determine its effect from this investigation."

Recognizing the limits of your evidence is a sign of scientific understanding.

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Listen Carefully to the Question

Sometimes students become nervous and answer a different question from the one the judge asked.

When a judge asks something:

1. Listen to the complete question.
2. Think briefly.
3. Answer the question directly.
4. Explain your reasoning.
5. Refer to evidence when appropriate.

It is perfectly acceptable to take a moment to think before answering.

If you do not understand the question, ask:

"Could you please repeat or rephrase the question?"

That is better than guessing what the judge meant.

Common Questions Judges May Ask

You should be prepared for questions such as:

Why did you choose this topic?

Explain your interest and the scientific reason the question is worth investigating.

What was your hypothesis?

State the prediction and scientific reasoning.

What was your independent variable?

Identify what you deliberately changed.

What was your dependent variable?

Identify what you measured.

How did you make your experiment a fair test?

Discuss control variables.

Why did you repeat your trials?

Explain that repeated trials help investigate variation and improve confidence in the results.

What was the most important result?

Identify the major pattern and support it with evidence.

Did your results support your hypothesis?

Answer based on the data.

Were there any anomalous results?

Identify them and explain how you handled them.

What was the biggest limitation?

Identify a genuine weakness in the investigation.

How would you improve the experiment?

Suggest a specific improvement connected to a limitation.

What would you investigate next?

Suggest a logical extension of the project.

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Practice Explaining Your Graph

Judges often focus on graphs because graphs summarize the evidence.

You should be able to explain:

• what the x-axis represents
• what the y-axis represents
• the overall pattern
• important values
• unusual results
• what the pattern suggests

For example:

"The x-axis shows salt concentration and the y-axis shows percentage germination. The overall pattern is downward. As salt concentration increased, germination generally decreased."

Then connect that observation to the conclusion.

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Explain Limitations

Every investigation has limitations.

A limitation is not simply:

"I made mistakes."

Instead, identify something specific that could have affected the quality of the evidence.

Examples include:

• small sample size
• human reaction time
• limited measuring precision
• uncontrolled temperature
• natural biological variation
• limited range of values
• inconsistent lighting
• difficulty keeping stirring rate constant

For example:

"One limitation was using a handheld stopwatch. Human reaction time introduced uncertainty into the timing measurements."

That identifies a specific issue.

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Suggest Specific Improvements

An improvement should address a limitation.

Limitation

Human reaction time affected stopwatch measurements.

Weak improvement

"Be more careful."

Stronger improvement

"Use electronic light gates to measure travel time automatically."

Another example:

Limitation

Only five seeds were used in each treatment.

Improvement

"Increase the sample size to 20 or more seeds per treatment to reduce the influence of natural variation."

A strong improvement explains how the investigation could produce better evidence.

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Confidence Does Not Mean Pretending to Know Everything

Presenting confidently does not mean:

• speaking extremely loudly
• memorizing every sentence
• pretending the experiment was perfect
• refusing to admit uncertainty
• using unnecessarily complicated vocabulary

Scientific confidence means being able to say:

This is what I investigated.

This is what I did.

This is what my evidence showed.

This is what I concluded.

These are the limitations of my investigation.

This is what I would improve.

That demonstrates genuine understanding.

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Body Language and Communication

How you communicate can help your audience understand you.

Try to:

• face the judge
• speak clearly
• use an appropriate volume
• avoid speaking too quickly
• point to your display when useful
• pause between important ideas
• listen carefully to questions

You do not need to stand completely still.

Natural gestures and movement are fine when they support your explanation.

Avoid Reading a Script Word for Word

A fully memorized speech can become difficult if you forget one sentence.

Instead, remember the structure of your explanation.

For example:

Question

↓

Why I chose it

↓

Hypothesis

↓

Method

↓

Main results

↓

Conclusion

↓

Limitations and improvements

This allows you to speak more naturally.

Your display can help remind you what comes next.

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Practice Before the Science Fair

Practice is one of the best ways to improve your presentation.

Try presenting to:

• a classmate
• a friend
• a family member
• your teacher
• yourself

Ask them to interrupt with questions.

This helps you practise moving between:

prepared explanation

and

unplanned questions.

You can also time your presentation so that your introduction does not become unnecessarily long.

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Practice Difficult Questions

Do not practise only the questions you hope judges will ask.

Also practise questions such as:

What was wrong with your experiment?

What would you change?

Why should I trust your results?

How do you know your conclusion is supported?

What other explanation could there be?

What surprised you?

What would happen if you extended the range?

You may not know the exact answers in advance, but practising scientific reasoning makes these questions easier to handle.

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What If the Hypothesis Was Not Supported?

Suppose you predicted:

Increasing light duration will increase plant growth.

But your results showed no clear relationship.

Do not say:

"My experiment failed."

Instead explain:

"The results did not provide clear evidence supporting my hypothesis. Plant growth varied between the treatments, but there was no consistent relationship with light duration."

Then consider why.

Possibilities might include:

• insufficient investigation time
• natural biological variation
• small sample size
• uncontrolled temperature
• limited light differences
• measurement uncertainty

An unsupported hypothesis can still produce an excellent scientific investigation.

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Separate Evidence from Possible Explanations

Suppose your plants receiving less water grew less.

Your evidence may show:

Plants receiving 20 mL per day had lower average growth than plants receiving 60 mL per day.

You might explain this using biological knowledge.

However, unless your experiment directly measured the mechanism, distinguish the observation from the explanation.

For example:

"The data show that plants receiving less water had lower average growth. One possible explanation is that reduced water availability limited processes required for growth."

This is more scientifically careful than claiming your experiment directly proved every part of the mechanism.

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Reflect on Feedback

Judges may give you suggestions or ask questions that reveal weaknesses you had not considered.

Feedback can help you identify:

• variables you overlooked
• better measuring techniques
• alternative explanations
• weaknesses in your graph
• problems with your procedure
• possible future investigations

Do not treat every difficult question as criticism.

A challenging question may reveal a useful direction for improving your scientific thinking.

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Record Useful Feedback

After presenting, it can be useful to write down:

What questions did judges ask?

Which questions were difficult to answer?

What strengths did they identify?

What limitations did they notice?

What improvements did they suggest?

What would I do differently next time?

This turns the judging experience into part of the scientific learning process.

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From Feedback to Improvement

Imagine a judge asks:

"How did you make sure each plant received the same light intensity?"

You realize that you controlled the number of hours of light but not the plants' distance from the lamp.

That feedback identifies a possible control-variable problem.

In a future investigation, you might:

• place all plants the same distance from identical lamps
• measure light intensity
• rotate plant positions systematically
• control other environmental conditions more carefully

Feedback has now improved your experimental design skills.

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Common Mistakes

Memorizing without understanding

If you understand your investigation, you can explain it even when the judge asks unexpected questions.

Reading directly from the board

Use the display as a visual aid rather than a script.

Explaining every small detail

Focus on the most important scientific information.

Saying only "My hypothesis was correct"

Explain what the evidence showed.

Ignoring numerical evidence

Refer to important measurements when they strengthen your explanation.

Hiding anomalous results

Discuss unusual results scientifically.

Making up an answer

If you do not know, say so.

Claiming the experiment proves too much

Keep conclusions within the limits of the evidence collected.

Saying the experiment had no limitations

Every investigation has limitations.

Recognizing them demonstrates scientific thinking.

Giving vague improvements

"Be more careful" is usually not enough.

Suggest a specific change to equipment, procedure, sample size, measurement technique, or variable control.

Speaking too quickly

Slow down enough for the judge to follow your explanation.

Treating feedback as failure

Feedback can reveal ways to design better investigations in the future.

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Key Terms

Presentation — An organized explanation of scientific work to an audience.

Judge — A person who evaluates and discusses a science fair investigation.

Scientific communication — The clear sharing of scientific questions, methods, evidence, reasoning, and conclusions.

Summary — A concise explanation containing the most important information.

Scientific evidence — Measurements and observations used to support or challenge a scientific claim.

Claim — A statement or conclusion that can be supported by evidence.

Reasoning — Scientific explanation connecting evidence to a claim.

Claim-Evidence-Reasoning (CER) — A structure for explaining a scientific conclusion using a claim, supporting evidence, and scientific reasoning.

Trend — A general pattern or direction in data.

Anomalous result — A result that differs noticeably from the general pattern.

Hypothesis — A testable prediction supported by scientific reasoning.

Independent variable — The factor deliberately changed during an investigation.

Dependent variable — The factor measured or observed.

Control variable — A factor kept as constant as reasonably possible.

Fair test — An investigation designed so that important variables other than the independent variable are controlled.

Conclusion — An evidence-based answer to the research question.

Justification — An explanation showing why a claim, decision, or conclusion is reasonable.

Limitation — A feature of an investigation that restricts the strength, precision, or interpretation of its evidence.

Improvement — A specific change that could increase the quality of an investigation.

Uncertainty — The degree of doubt associated with a measurement or conclusion.

Reliability — The consistency or dependability of experimental results.

Sample size — The number of individual observations, organisms, objects, or measurements included in a study.

Feedback — Information provided by others that can be used to evaluate and improve work.

Reflection — Careful consideration of what was learned, what worked, and what could be improved.

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Key Takeaways

• Your science fair presentation should tell the story of your investigation.
• Begin with a clear explanation of your research question.
• Explain why the question was worth investigating.
• Understand the science behind your project.
• Explain your hypothesis using scientific reasoning.
• Be prepared to identify your independent, dependent, and control variables.
• Summarize the experimental method rather than reading every step.
• Use your display as a visual aid, not as a script.
• Know the main patterns in your results.
• Use important numerical evidence when it strengthens your explanation.
• Explain graphs rather than simply pointing to them.
• Use Claim → Evidence → Reasoning to support scientific explanations.
• Your conclusion should answer your research question.
• Keep conclusions within the limits of your evidence.
• Do not hide anomalous or unexpected results.
• Be prepared to discuss limitations.
• Suggest specific improvements that address those limitations.
• An unsupported hypothesis does not mean an unsuccessful investigation.
• It is scientifically responsible to say "I don't know" when the evidence does not provide an answer.
• Listen carefully to judges' questions before responding.
• Ask for clarification when you do not understand a question.
• Confidence comes primarily from understanding your investigation.
• Practise explaining the project without memorizing every sentence.
• Practise answering difficult and unexpected questions.
• Use judges' feedback to identify improvements for future investigations.

A strong presentation ultimately communicates four things:

I understand what I investigated.

I understand the evidence I collected.

I can explain why my conclusion follows from that evidence.

I understand how my investigation could be improved.