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Science

Grade 3 - Natural Sciences

📚 8 Topics⏱ïļ 50 min read
Section 1

Human Body Systems

Our body is made up of different organ systems that work together to keep us alive and healthy.

Skeletal System

Function: Supports the body, protects organs, and helps us move

  • â€Ē We have 206 bones in our body
  • â€Ē Skull protects the brain
  • â€Ē Ribcage protects the heart and lungs
  • â€Ē Backbone (spine) supports the body

Muscular System

Function: Helps the body move

  • â€Ē We have over 600 muscles
  • â€Ē Muscles are attached to bones
  • â€Ē The heart is also a muscle
  • â€Ē Exercise makes muscles stronger

Digestive System

Function: Breaks down food into nutrients

  • â€Ē Mouth - chews and breaks down food
  • â€Ē Esophagus - tube that moves food to stomach
  • â€Ē Stomach - digests food with acids
  • â€Ē Intestines - absorb nutrients

Respiratory System

Function: Helps us breathe

  • â€Ē Nose/Mouth - air enters here
  • â€Ē Trachea - windpipe that carries air
  • â€Ē Lungs - take in oxygen, release carbon dioxide
  • â€Ē Diaphragm - muscle that helps lungs expand

Circulatory System

Function: Moves blood throughout the body

  • â€Ē Heart - pumps blood (beats ~100,000 times/day)
  • â€Ē Blood vessels - tubes that carry blood
  • â€Ē Arteries - carry blood away from heart
  • â€Ē Veins - carry blood back to heart
Section 2

Plant Life Cycle

Plants go through a life cycle - a series of stages from seed to adult plant.

Life Cycle of a Flowering Plant

🌰

1. Seed

→
ðŸŒą

2. Germination

→
ðŸŠī

3. Seedling

→
ðŸŒŋ

4. Adult Plant

→
ðŸŒļ

5. Flower

→
🍎

6. Fruit & Seeds

What Plants Need to Grow

☀ïļ

Sunlight

For photosynthesis

💧

Water

For nutrients

🌎ïļ

Air

Carbon dioxide

ðŸŠĻ

Soil

For minerals

Photosynthesis

Photosynthesis is how plants make their own food using:

Sunlight ☀ïļ+Water 💧+Carbon Dioxide 🌎ïļ=Glucose (Food) 🍎+Oxygen ðŸ’Ļ
Section 3

Animal Habitats

A habitat is the natural home or environment where an animal lives. Animals have special features that help them survive in their habitat.

Forest Habitat ðŸŒē

Trees, plants, and shade

Animals: Monkeys, deer, birds, squirrels, snakes

Adaptation: Good climbing, camouflage

Ocean Habitat 🌊

Saltwater, coral reefs

Animals: Fish, whales, dolphins, sharks, jellyfish

Adaptation: Fins, gills, streamlined body

Desert Habitat 🏜ïļ

Hot, dry, very little water

Animals: Camel, lizard, scorpion, snake

Adaptation: Store water, active at night

Polar Habitat ❄ïļ

Very cold, ice and snow

Animals: Polar bear, penguin, seal, walrus

Adaptation: Thick fur/blubber, white color

Freshwater Habitat 🏞ïļ

Rivers, lakes, ponds

Animals: Frog, fish, turtle, duck, beaver

Adaptation: Webbed feet, can swim

Grassland Habitat ðŸŒū

Open areas with grass

Animals: Lion, zebra, elephant, giraffe

Adaptation: Fast runners, good eyesight

Section 4

Ecosystems

An ecosystem is a community of living things (plants and animals) and non-living things (water, air, soil) that interact with each other.

Food Chain

A food chain shows how energy passes from one living thing to another.

☀ïļ

Sun

Energy

→
ðŸŒą

Grass

Producer

→
🐰

Rabbit

Herbivore

→
ðŸĶŠ

Fox

Carnivore

→
ðŸĶ…

Eagle

Top Predator

Producers

Plants that make their own food (grass, trees, algae)

Consumers

Animals that eat other living things

Decomposers

Break down dead things (fungi, bacteria, worms)

Types of Consumers

TypeWhat They EatExamples
HerbivorePlants onlyCow, rabbit, deer, elephant
CarnivoreMeat onlyLion, shark, eagle, snake
OmnivorePlants and meatHuman, bear, pig, chicken
Section 5

Properties of Matter

Matter is anything that has mass and takes up space. Everything around us is made of matter!

Three States of Matter

🧊

Solid

  • â€Ē Has definite shape
  • â€Ē Has definite volume
  • â€Ē Particles tightly packed
  • â€Ē Examples: ice, rock, wood
💧

Liquid

  • â€Ē Takes shape of container
  • â€Ē Has definite volume
  • â€Ē Particles move freely
  • â€Ē Examples: water, juice, oil
ðŸ’Ļ

Gas

  • â€Ē No definite shape
  • â€Ē No definite volume
  • â€Ē Particles spread out
  • â€Ē Examples: air, steam, oxygen

Changes in State

SOLID
→ melting← freezing
LIQUID
→ evaporation← condensation
GAS

Physical Properties

Color

red, blue, green

Size

big, small

Shape

round, square

Texture

smooth, rough

Mass

heavy, light

Hardness

hard, soft

Flexibility

bendable, stiff

Odor

smelly, odorless

Section 6

Forces and Motion

A force is a push or pull that can make objects move, stop, or change direction.

Push Force 👋

Moving something away from you

  • â€Ē Pushing a cart
  • â€Ē Kicking a ball
  • â€Ē Closing a door

Pull Force ðŸĪš

Moving something toward you

  • â€Ē Pulling a wagon
  • â€Ē Opening a drawer
  • â€Ē Tug of war

Types of Forces

🌍

Gravity

Pulls objects toward Earth. Makes things fall down.

ðŸ§ē

Magnetism

Attracts or repels magnetic materials like iron.

✋

Friction

Slows down or stops moving objects. Rough surfaces have more friction.

Motion

Motion is when something changes position. Objects can move in different ways:

Straight lineZigzagCircularBack & forth
Section 7

Earth and Weather

Layers of the Earth

🌋

Crust

The outer layer we live on. Made of rocks and soil.

ðŸ”Ĩ

Mantle

Hot layer of melted rock below the crust.

⭐

Core

The center of Earth. Very hot metal (iron).

Types of Weather

☀ïļ

Sunny

Clear sky, hot

🌧ïļ

Rainy

Rain falling

☁ïļ

Cloudy

Clouds cover sky

ðŸ’Ļ

Windy

Strong winds

⛈ïļ

Stormy

Thunder, lightning

❄ïļ

Snowy

Snow falling

ðŸŒŦïļ

Foggy

Thick mist

🌈

Rainbow

After rain + sun

Water Cycle

💧

Evaporation

Water → vapor

→
☁ïļ

Condensation

Vapor → clouds

→
🌧ïļ

Precipitation

Rain/snow falls

→
🏞ïļ

Collection

Water gathers

Section 8

The Solar System

Our solar system is made up of the Sun and everything that orbits around it, including 8 planets.

The 8 Planets (in order from the Sun)

Remember: "My Very Eager Mother Just Served Us Nachos"

1.

Mercury

Closest to Sun, smallest

2.

Venus

Hottest planet

3.

Earth

Our home, has water

4.

Mars

The Red Planet

5.

Jupiter

Largest planet

6.

Saturn

Has beautiful rings

7.

Uranus

Tilted on its side

8.

Neptune

Farthest, very cold

The Sun ☀ïļ

  • â€Ē A star (ball of hot gas)
  • â€Ē Center of our solar system
  • â€Ē Gives us light and heat
  • â€Ē Much bigger than all planets combined

The Moon 🌙

  • â€Ē Earth's natural satellite
  • â€Ē Orbits around Earth
  • â€Ē Has phases (new, crescent, full)
  • â€Ē Causes ocean tides

Day and Night

Earth rotates (spins) on its axis. The side facing the Sun has day, the side facing away has night. One complete rotation = 24 hours (1 day).

Key Takeaways

✓Body systems work together: skeletal, muscular, digestive, respiratory, circulatory
✓Plants need sunlight, water, air, and soil to grow
✓Animals have adaptations to survive in their habitats
✓Food chains show how energy flows: producers → consumers → decomposers
✓Matter exists in three states: solid, liquid, gas
✓Forces (push, pull, gravity, friction) cause motion
✓Water cycle: evaporation → condensation → precipitation → collection
✓Our solar system has 8 planets orbiting the Sun