Preschool Lesson Plan: Science for Toddlers – Sink or Float

Looking for a hands-on, interactive way to teach science to toddlers? Sink or Float Science for Toddlers is a perfect activity to inspire curiosity in young minds. Using everyday household items and a little water, this interactive experiment enables children to learn basic physics concepts like buoyancy and density, without realising it! It’s a wonderful way to promote early STEM learning through sensory discovery, prediction, and exploration.

Age Group:
2.5 – 5 years (Toddlers & Preschoolers)
Duration:
1 lesson period (45–60 minutes)
Theme:
Science Through Sensory Exploration

Learning Objectives:

Children will be able to:

1. Identify the difference between sinking and floating objects
2. Observation and simple reasoning to make predictions
3. Hands-on science play with water and household objects
4. Vocabulary words like “sink,” “float,” “heavy,” and “light”
5. Begin developing the basic science process skills: predicting, testing, and observing

Materials Needed:

• Large, transparent tub or basin of water
• A waterproof towel or spill mat
• General household items (rubber duck, spoon, coin, sponge, plastic cup, rock, toy boat, wooden block, leaf, ball)
• Printable prediction chart or plain drawing worksheet
• Crayons or markers
• Smocks or aprons (optional)

Introduction (10 Minutes):

1. Warm-Up and Welcome:
   Begin with a brief welcome song. Have the children sit in a circle and introduce today’s theme: science fun with water!
2. Hook Question:
   Show a rock and a toy boat and ask:
   • “What do you think will happen if we put this in the water?”
   • “Will it sink to the bottom or float on top?”
3. Introduce the Concept:
   Explain: “Today, we’re going to do Sink or Float – Simple Science for Toddlers. That means we’ll test different things to see what stays on top of the water and what goes to the bottom.”

Main Activity – Sink or Float Exploration (30 Minutes):

Step 1: Make Predictions (10 Minutes)

• Show each object to the group one at a time.
• Ask: “Do you think this will sink or float?”
• Have each child point to “sink” or “float” on a simple visual chart or raise their hand.
• Use language that toddlers can understand:
  • “Do you think this will float on top like a duck, or sink like a rock?”

Step 2: Conduct the Experiment (15 Minutes)

• Have each child gently drop something into the water.
• Observe together to see what happens.
• Record the result on the chart in pictures or symbols.
• Say aloud: “The sponge floats! Let’s place it on the float side.”

Step 3: Simple Explanation (5 Minutes)

• Keep the explanation short and age-related:
  • “Some things are filled with air, and that’s why they float.”
  • “Heavy objects or objects with no air will usually sink.”
• Use a ball and a spoon to demonstrate and compare.

Group Discussion and Review (10 Minutes):

• Get each child to tell you something they discovered:
  • “What floated?”
  • “What sank?”
• Reinforce with vocabulary:
  • “You’re correct, the coin sank as it’s heavy!”
• Use this moment to encourage children to be curious and amazed.

Reinforcement Activities (10 Minutes):

1. Sink or Float Colouring Worksheet
   Children colour the objects that floated one colour, and those that sank another.
   This is for a visual reinforcement of the concept.
2. Story Connection
   Read a book like Things That Float and Things That Don’t by David A. Adler.
   Bring the story back to the activity for the day.

Assessment:

Monitor and document each child’s participation:

Use open-ended questions to check comprehension:

• “Why do you think the ball floated?”
• “Can you show me something that sinks?”

Setting Up the Learning Space:

• A water tub
• Floating toys
• Towels and aprons
• A chartboard for predictions
• This encourages free exploration during playtime.

Free Download Preschool Lesson Plan: Sink or Float Science for Toddlers