Science Trivia for Kids: Questions & Answers

These science trivia questions for kids are built around the topics elementary learners meet most often: space, the human body, Earth and weather, plants, matter and simple forces. Every answer includes a short explanation so the quiz doubles as a learning activity.

For related rounds, try our science trivia questions, trivia questions for kids and the Trivia hub.

How to Play

• Read the full question before anyone answers.
• Award 1 point for each correct answer.
• Use the final section as a tie-breaker if scores are close.
• For classrooms or families, pause after each answer for the short explanation.

Space & Planets

Q1. How many planets are in our solar system?

Answer: Eight. Why: NASA recognizes eight planets orbiting the Sun.

Q2. What is the closest star to Earth?

Answer: The Sun. Why: The Sun is the star at the center of our solar system.

Q3. Which planet is known as the Red Planet?

Answer: Mars. Why: Iron minerals in Martian soil give the surface a reddish color.

Q4. What is the largest planet in our solar system?

Answer: Jupiter. Why: Jupiter is the largest planet by mass and diameter.

Q5. Which planet is famous for its bright rings?

Answer: Saturn. Why: All four giant planets have rings, but Saturn’s are the most prominent.

Q6. What galaxy contains our solar system?

Answer: The Milky Way. Why: Our solar system is located in the Milky Way galaxy.

Q7. What causes day and night on Earth?

Answer: Earth’s rotation. Why: Earth spins once roughly every 24 hours.

Q8. What object orbits Earth and helps cause ocean tides?

Answer: The Moon. Why: The Moon’s gravity is a major cause of Earth’s tides.

Human Body & Life

Q9. What organ pumps blood through the body?

Answer: The heart. Why: The heart pushes blood through the circulatory system.

Q10. How many bones are in a typical adult human skeleton?

Answer: 206. Why: Most adults have 206 bones, though natural variation can occur.

Q11. Which blood cells carry most of the oxygen in human blood?

Answer: Red blood cells. Why: Hemoglobin in red blood cells binds oxygen.

Q12. What organ helps us breathe by exchanging oxygen and carbon dioxide?

Answer: The lungs. Why: Gas exchange happens in tiny air sacs called alveoli.

Q13. What is the body’s largest organ?

Answer: The skin. Why: Skin covers and protects the body’s outer surface.

Q14. What molecule carries genetic information in most living things?

Answer: DNA. Why: DNA stores hereditary information.

Q15. What process do many cells use to divide into two similar daughter cells?

Answer: Mitosis. Why: Mitosis supports growth and tissue repair.

Q16. What do we call animals that eat only plants?

Answer: Herbivores. Why: Herbivores feed mainly on plant material.

Earth, Weather & Water

Q17. What process changes liquid water into water vapor?

Answer: Evaporation. Why: Heat energy helps water molecules enter the air as vapor.

Q18. What process changes water vapor into liquid droplets?

Answer: Condensation. Why: Condensation helps form clouds.

Q19. What do we call water falling from clouds as rain, snow, sleet or hail?

Answer: Precipitation. Why: Precipitation returns water from the atmosphere to Earth’s surface.

Q20. What layer of gases surrounds Earth?

Answer: The atmosphere. Why: Earth’s atmosphere contains nitrogen, oxygen and other gases.

Q21. What is the most abundant gas in Earth’s atmosphere?

Answer: Nitrogen. Why: Nitrogen makes up about 78 percent of dry air.

Q22. What instrument measures temperature?

Answer: A thermometer. Why: Thermometers measure how hot or cold something is.

Q23. What instrument records earthquake waves?

Answer: A seismometer. Why: Seismometers detect and record ground motion.

Q24. What type of rock forms when magma or lava cools?

Answer: Igneous rock. Why: Granite and basalt are common igneous rocks.

Plants, Light & Matter

Q25. What process lets green plants make sugars using light?

Answer: Photosynthesis. Why: Plants use light energy, water and carbon dioxide to make sugars.

Q26. Which part of a plant usually absorbs water from the soil?

Answer: The roots. Why: Roots take up water and minerals.

Q27. What green pigment helps plants capture light energy?

Answer: Chlorophyll. Why: Chlorophyll absorbs light used in photosynthesis.

Q28. What common substance has the chemical formula H2O?

Answer: Water. Why: Each molecule has two hydrogen atoms and one oxygen atom.

Q29. What is the chemical symbol for oxygen?

Answer: O. Why: O is the element symbol for oxygen.

Q30. What is the chemical symbol for gold?

Answer: Au. Why: Au comes from the Latin word aurum.

Q31. What are the three common states of matter taught in elementary science?

Answer: Solid, liquid and gas. Why: Matter can also exist in other states, but these three are the most familiar.

Q32. What is the change from solid directly to gas called?

Answer: Sublimation. Why: Dry ice is a familiar example.

Forces & Science Challenge

Q33. What force pulls objects toward Earth?

Answer: Gravity. Why: Gravity attracts objects with mass toward one another.

Q34. What is the SI unit of force?

Answer: The newton. Why: The unit is named after Isaac Newton.

Q35. What is the smallest prime number?

Answer: 2. Why: It is also the only even prime number.

Q36. What kind of energy is stored in food?

Answer: Chemical energy. Why: Cells release usable energy through chemical reactions.

Q37. What simple machine is a ramp?

Answer: An inclined plane. Why: An inclined plane helps move objects between different heights.

Q38. What happens to most materials when they are heated?

Answer: They expand. Why: Particles generally move farther apart as temperature rises.

Q39. What is the pH of pure water at about room temperature?

Answer: About 7. Why: At roughly 25°C, pure water is neutral at pH 7.

Q40. What is the name of the path a planet follows around the Sun?

Answer: An orbit. Why: Gravity keeps planets moving in their orbits.

Reliable Sources

Important historical and scientific facts were checked against established government, museum, science or educational references:

• NASA Science for Kids — Solar System
• NASA Space Place — Planets
• U.S. Geological Survey — Water Cycle for Kids
• National Human Genome Research Institute — DNA Fact Sheet

FAQ

What age is this science trivia for? The wording is aimed mainly at ages 6–12, with a few challenge questions for older elementary learners.

How can teachers use this quiz? Use one section as a bell-ringer, science review or team game, then ask students to explain the ‘why’ in their own words.