How to Write an Informative Speech (Plus 40 Topic Ideas)

An informative speech teaches the audience something. Its goal is not to change minds or move people to action, but to help them understand a topic more clearly than they did before. It’s one of the most common assignments in public speaking classes, and one of the most useful skills in professional life, where explaining a project, a process, or a set of results is part of almost every job.

The challenge is that “informative” can easily become “boring.” This guide shows you how to choose a topic, organize your information so it’s easy to follow, explain complex ideas clearly, and keep your audience engaged from start to finish.

Informative vs. Persuasive Speeches

	Informative	Persuasive
Goal	Increase understanding	Change beliefs or behavior
Speaker’s role	Teacher	Advocate
Typical verbs	explain, describe, demonstrate, define	convince, urge, argue, recommend
Example	How solar panels generate electricity	Why our school should install solar panels

The line can blur: any choice about what to include can subtly persuade. But in an informative speech, you should present information fairly and avoid arguing for a position. If you find yourself saying “should,” you may be drifting into persuasion.

The Four Types of Informative Speeches

1. Speeches about objects

Anything tangible: a place, a structure, an invention, an animal, a person. Examples: the James Webb Space Telescope, the Great Barrier Reef, the bicycle.

2. Speeches about processes

How something works or how to do something. When the speaker shows the audience how, it’s often called a demonstration speech. Examples: how vaccines train the immune system, how to change a bicycle tire, how a bill becomes law.

3. Speeches about events

Something that happened or regularly happens. Examples: the first Moon landing, the Chernobyl disaster, the Day of the Dead festival.

4. Speeches about concepts

Abstract ideas, theories, beliefs, or principles. These are the most challenging because the topic can’t be seen or touched. Examples: compound interest, the placebo effect, cognitive biases, minimalism.

Step 1: Choose and Narrow Your Topic

Pick a topic that:

• Interests you. Your enthusiasm will be visible and contagious.
• Is new to your audience. If they already know it, they won’t learn anything. Find a fresh angle.
• Fits the time limit. “The history of the Roman Empire” cannot be covered in five minutes. “How Roman aqueducts carried water without pumps” can.

Narrowing is essential. Most informative speeches fail because they try to cover too much and end up saying nothing in depth. For five step-by-step methods, see how to narrow down speech topics.

Too broad	Narrowed
The ocean	How bioluminescent animals create light
Sleep	What happens in the brain during REM sleep
Artificial intelligence	How recommendation algorithms decide what you see next
Japan	The meaning and rules of a Japanese tea ceremony

Step 2: Write a Specific Purpose and Central Idea

Specific purpose: what you want the audience to understand.

To inform my audience about how compound interest works.

Central idea: the whole speech in one sentence.

Compound interest is interest earned on both your original money and on interest you’ve already earned, which is why small, early savings can grow dramatically over time.

Step 3: Organize Your Main Points

Choose an organizational pattern that fits your topic type:

• Chronological: for events, histories, and processes (“first… then… finally”)
• Spatial: for places and physical objects (“from the roots to the canopy”)
• Topical: for dividing a subject into categories (“three types of volcanoes”)
• Cause–effect: for explaining why something happens

Stick to two to four main points, so the audience can remember them.

Example (compound interest, topical/process):

1. What interest is, and the difference between simple and compound interest
2. How compounding grows money over time, with a worked example
3. The two factors that matter most: time and rate

Step 4: Explain Ideas Clearly

This is where informative speeches succeed or fail. Your job is to make complex ideas simple without making them wrong.

Start from what the audience knows

Connect new information to something familiar. If you’re explaining how a computer’s memory works, start with the familiar idea of a desk (short-term workspace) versus a filing cabinet (long-term storage).

Use analogies

An analogy explains the unfamiliar in terms of the familiar:

Compound interest is like a snowball rolling downhill. It starts small, but as it rolls it picks up more snow, and the bigger it gets, the faster it grows.

Define key terms

Introduce technical terms only when necessary, define them in plain language the first time, and use them consistently afterward.

Use concrete examples and numbers

Abstract explanations become clear with a specific example:

Imagine you save $1,000 at 5% interest per year. With simple interest, you earn $50 every year; after 30 years, you’d have $2,500. With compound interest, you earn interest on your interest. After 30 years, you’d have about $4,322, without adding another cent.

Round numbers for listeners, and translate large figures into relatable comparisons.

Repeat and summarize

Listeners can’t reread. Preview your points in the introduction, use clear transitions between them, and summarize at the end. Briefly restating a complex idea in different words (“In other words…”) helps it stick.

Step 5: Keep the Audience Engaged

Information alone doesn’t hold attention. Build in engagement:

• Open with a hook: a surprising fact, a question, a short story, or a demonstration. (“If you had saved just a few dollars a day starting at age 18…”)
• Tell stories: brief, relevant stories make information memorable.
• Ask the audience to participate: “Raise your hand if…” or “Think of the last time you…”
• Make it relevant: explicitly tell the audience why this matters to them.
• Vary your delivery: change pace, use pauses, and move purposefully. See our public speaking tips.

Step 6: Use Visual Aids Effectively

Visual aids can make an informative speech much clearer, especially for processes, data, and objects. But poorly designed slides can also distract.

Do:

• Use one idea per slide.
• Use images, diagrams, and simple charts rather than text.
• Keep text to a few keywords, in a large, readable font.
• Make sure visuals are visible from the back of the room.
• Practice with your visuals so transitions are smooth.

Don’t:

• Put your script on your slides and read it aloud.
• Use complex charts that need a long explanation.
• Turn your back to the audience to read the screen.
• Rely on technology without a backup plan.

Ask yourself: would the speech be clearer without this slide? If yes, cut it.

Step 7: Cite Your Sources Orally

In an informative speech, your credibility depends on your sources. Mention them naturally as you speak:

According to the U.S. Securities and Exchange Commission’s investor education website… A 2023 report from the World Health Organization found that…

Name the source and, where relevant, the date. You don’t need full citations aloud, but your instructor may require a written reference list.

Sample Informative Speech Outline

Topic: How compound interest works Specific purpose: To inform my audience about how compound interest works and why time matters Central idea: Compound interest is interest earned on interest, which is why small, early savings can grow dramatically.

I. Introduction

• A. Hook: “What if I told you that the best financial decision you can make requires no skill, only time?”
• B. Relevance: everyone in this room will save, borrow, or invest
• C. Credibility: what I learned while researching for my economics class
• D. Preview: what compound interest is, how it grows, and what matters most

II. Body

• A. What compound interest is
  • 1. Simple interest: interest on the original amount only
  • 2. Compound interest: interest on the original amount plus past interest
  • 3. Analogy: the snowball
• B. How it grows over time
  • 1. Worked example: $1,000 at 5% for 30 years
  • 2. Simple ($2,500) vs. compound (about $4,322)
• C. What matters most
  • 1. Time: starting early has an outsized effect
  • 2. Rate: small differences add up
  • 3. It works in reverse for debt, such as credit card balances

III. Conclusion

• A. Summary: interest on interest, growth over time, time and rate
• B. Final thought: “The snowball doesn’t need to be big. It just needs a long hill.”

40 Informative Speech Topic Ideas

Science and nature

1. How vaccines train the immune system
2. Why the sky is blue
3. How bees communicate through dance
4. What causes the northern lights
5. How tardigrades survive extreme conditions
6. How plate tectonics creates earthquakes
7. How the human eye sees color
8. Why we dream

Technology 9. How GPS knows where you are 10. How recommendation algorithms work 11. How noise-cancelling headphones work 12. What happens when you send an email 13. How 3D printing works 14. How touchscreens detect your finger 15. How password managers keep data secure

History and culture 16. The history of the printing press 17. How the Rosetta Stone helped decode hieroglyphics 18. The origins of the Olympic Games 19. The Silk Road and its impact on trade 20. The story behind a national holiday in your country 21. How ancient Polynesians navigated the Pacific 22. The meaning of Día de los Muertos 23. The history of written language

Health and psychology 24. What happens in the body during exercise 25. How habits form 26. The placebo effect 27. How caffeine affects the brain 28. Common cognitive biases 29. The science of procrastination 30. How memory works

Everyday life and skills 31. How compound interest works 32. How to read a nutrition label 33. How credit scores work 34. How recycling is actually processed 35. How to perform basic first aid for burns 36. How elections are run in your country 37. How to identify misinformation online 38. How coffee goes from farm to cup 39. How sign languages differ around the world 40. How a bill becomes law

Informative Speech Checklist

• My topic is narrow enough for the time limit.
• I have a clear specific purpose and central idea.
• I have two to four main points in a logical pattern.
• I explain complex ideas with analogies, examples, and plain definitions.
• I engage the audience with a hook, stories, and relevance.
• My visual aids are simple and support (not replace) my words.
• I cite sources aloud.
• I’ve stayed informative and haven’t drifted into persuasion.

To draft your full script, follow our step-by-step guide on how to write a speech.