Lesson Plan

Sink or Float!

Hand on activity including observation documentation.
Susan P.
Media specialist/librarian
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  • Students will categorize a variety of objects according to observable characteristics (sink or float).
  • Students will be encouraged to observe that the same objects will sink or float every time.
  • All students will predict whether given objects sink or float. Then, students will characterize those objects based on their observations.
  • Students should accurately predict five out of seven times whether an object sinks or floats.

Science concepts:
•Substances which are less dense than water float (eg oil) while
more dense substances sink (eg cheese)
•Objects which sink displace their own volume of water
•Objects which float displace their own weight of water
•Air bubbles increase the buoyancy of a sealed object
Materials and equipment
•Aquarium / Clear plastic tub
•Assortment of objects (see below)

Mystery items to test
Students attempt to stump the class
with bizarre or mundane mystery items
from home.

Some suggestions for items to play “Will it float?”:

  • ŒFruit
  • ŒSoft drink (diet / regular)
  • ŒMilk
  • ŒCan of beans
  • ŒGlue stick
  • ŒYoghurt
  • ŒChocolate bars
  • ŒNuts
  • ŒToothpaste
  • ŒShampoo
  • ŒCheese
  • ŒSmall screw driver (plastic or wooden handle)

Student Record Sheet


Grades 3
All Notes
Teacher Notes
Student Notes

1 Hook

  • Teacher will open the NOVA website to review video on buoyancy.
  • Teacher discusses with students how water is mentioned in the rhyme.
  • Teacher asks students to mention different ways water is used in our everyday lives.
  • Teacher writes on chart paper students’ responses about the use of water in our lives.
Student Instructions
  • The students will listen and watch the video on buoyancy.
  • Students brainstorm the different ways we use water in our everyday life.
  • Students read their ideas written in the chart paper.

2 Direct Instruction

Activity: Exploring
  • Teacher discusses the terms sink, float, and prediction.
  • Teacher explains the terms by putting objects in the water and telling students that when something goes down the water, we said it sinks. If something stays on top of the water then it floats.
  • Teacher holds up, one item at the time, and asks students to put thumbs up if they think it will float or thumbs down if they think the item will sink.
  • Teacher explains to students that by guessing if an object will sink or float they are making a prediction.
  • Teacher uses a prediction chart, containing the picture of several items, to ask students if those items will float or sink.
  • Teacher demonstrates the objects in a pail of water.
  • Teacher monitors students to make sure they are following the right procedure while doing this project.
Student Instructions
  • Students hear the words and read them aloud.
  • Students observe the teacher while she explains the terms.
  • Students repeat the terms aloud.
  • Students do as told.
  • Students predict if different items will sink or float.
  • Students take turns taking one illustration at the time. They will place it either on the float or sink part of the chart making predictions.
  • Students observe the items float or sink in the water and check if their predictions were correct.
  • Students predict whether an item will sink or float in the water.
  • Students will record their predictions on the Sink or Float activity sheet. They will write an S for sink or F for float.
  • Students will take turns putting one item at the time into the pail of water, then recording the actual sink or float outcome on their activity sheets.

3 Explain

Activity: Conversing
  • Teacher asks students what the terms sink, float, and prediction means to them.
  • Teacher talks to students about their prediction and if those predictions were right or not.
  • Teacher tells students that it is OK to prove a prediction wrong. 
Student Instructions
  • Students explain the terms in their own words.
  • Students observe the chart and verify their predictions.
  • Students will understand that predictions are not always right.

4 Extend

Activity: Drawing

Teacher repeats the experiment two more times using the same objects.

  • Teacher asks some of the students to look around the classroom for objects that will sink. She asks different students to look for objects that will float.
  • Teacher counts how many students predicted an object will sink or float.
  • Teacher will graph the results.


Student Instructions
  • Students observe the experiment two more times, noting that the same objects will sink or float every time.
  • Students look for objects around the classroom try to find consistency in the way objects behave.
  • Students need to be able to categorize the objects as objects that sink or float.
  • Students see the result of their prediction.
  • Students help teacher graphing the results.

5 Evaluates

Activity: Assessing
  • Teacher collects students’ data sheet and check their predictions.
  • Teacher observes students progress while they are doing the experiment.
Student Instructions
  • Students reflect about their predictions and results in their own data sheet.
  • Students are able to evaluate their own predictions in their data sheet by looking at her corrected data sheet.