Solid or Liquid?

Learning Objectives

After this activity, students should be able to:

  • sort and classify items according to specific characteristics
  • describe how our five senses help us learn about different materials

Materials List

For groups to share:

Bring in a selection of the assorted materials below (each has different properties). You will need enough materials so that when the class is broken up into groups of two, each group can have a different material to examine. Each of the following should be in an open top container (i.e. plastic cup) for observation. Some suggestions:

  • Wooden blocks
  • Jell-O®
  • Water
  • Ice
  • soap (bar and liquid forms)
  • sand
  • gravel/pebbles/marbles
  • vegetable oil
  • Elmer's glue
  • Bubble gum
  • cotton balls
  • Scotch tape
  • Eggs: hard boiled or raw
  • Saran Wrap®
  • Marshmallows
  • slime
  • silly putty
  • sugar
  • molasses
  • honey
  • Sticky tack
  • Sandpaper
  • Wool

For each group:

  • 2 pieces of Bristol board (one red, one blue for example)
  • paper towels and a paper plate


Gather the class together and discuss the differences between solids and liquids. One of the key differences is that a solid keeps its form while a liquid fills up the space of its container, taking the shape of the container. You can illustrate this with a glass vase: fill the vase first with gravel/pebbles/marbles. Ask the students if the vase is full – they will likely say yes. Then add sand to the vase and ask the students if the vase is full. Then add water to the vase and ask the students if the vase is full. You can show them that the solid objects (gravel and sand) do not completely fill the container since you are able to add more material, whereas the liquid (water) does.

Ask the class to give you some examples of each form of matter. While you are discussing the differences, you can ask the students to think about the different uses of materials, both solid and liquid. For example, you could ask students whether they should build a house with solid bricks or a liquid such as water. Or, you could ask them whether it is easier to pour milk or ice cream on their cereal in the morning!

Certain types of scientists study materials. They work with materials to decide which is best suited for a certain purpose. All materials have properties that can be identified. One of the first things you can identify is whether the object is a solid or a liquid. Next, you can use your five senses to learn more about the material. Who knows what your five senses are? They are: sight, smell, touch, sound and taste. What can our senses help us learn about materials? (Answer: How big, heavy, smelly, rough, smooth, flexible, soft, hard, colorful, loud, quiet, etc. a specific material is.)
In this activity, the students will sort materials based on their properties. Students will make use of sight and touch in this activity to make distinctions based on their observations.

Lesson Background & Concepts for Teachers

Body of Lesson

Conduct the Introduction/Motivation section with the students. Split the class into groups of two students each.
Ask the groups to sort their samples by separating the solids from the liquids. Ask each group to place the solids on the red Bristol board and the liquids on the blue Bristol board. Encourage the students to perform tests on the samples: does it pour? Can it stand by itself and maintain its shape? Students can use the paper plate provided with a small dab of the material to perform these tests.
Follow-up activities: ask the students to sort materials based on other properties (hard vs. soft; dark colours vs. light colours; rough vs. smooth, heavy vs. light, etc.). Emphasize for the students that understanding all of an object’s properties is important for being able to use materials appropriately.

Lesson Closure

Gather the class together and hold a brief discussion of what just took place. Ask if there was anything particularly difficult about distinguishing between solids and liquids, for example. Were there any materials that were difficult to categorize? If you noticed any problems students were having you can bring these up and ask how students solved them. Ask the students about the five senses: which ones were used in this activity to classify materials? Finish up the lesson by discussing again the differences between solids and liquids. Ask the class together to tell you whether each material is a solid or a liquid, from a sampling of the different materials used in the activity

Adapted from Teach Engineering