Volume of Liquid

The Meaning of Volume of Liquid 

Volume of liquid refers to the capacity of liquids in the containers. Capacity can be measured by using non standard units (more or less) and in standard units in millimeters (ml) and litters (l) in the metric system. Investigations amount of liquids which can be poured between containers of different shapes and sizes. Exploration of capacity or volume of liquid involves manipulation of containers of various sizes that may either be collected or purchased for classroom activities. A cheap way to do the activities is to have your students collect some containers such as mineral water bottles, soft drink cans, vases etc which can be found around them.
Teacher can display those collections of containers in a learning centre for students to explore capacity measurement. Every learning centre should have at least a standard graduated measuring cylinder in liters and millimeters. This is to enable the students to measure volume of liquids especially in standard units. 

Misconception On Capacity

Just like in other subjects, students face  some  misconceptions in mathematics. These misconceptions are derived from their prior knowledge and experiences with numbers in their everyday lives. These misconceptions hinder the learning process, because they are tightly held by students. Their teachers need to provide tangible experiences to break these misconceptions.

Eliminating  mathematic misconceptions is difficult and merely repeating a lesson or extra practice will not help. Telling students were they are mistaken will not work either. Recognizing student misconceptions and immediately focusing a discussion on the misconception is important. Providing guiding questions using inductive reasoning is the best approach.

Misconception 1: Mathematical language – confusion between liquid volume and capacity.

The volume of an object is the amount of 3-D space that it occupies. Liquid volume and solid volume are measured in different units, although the concepts are the same. Liquid volume is measured in millilitres and litres and solid volume in cubic centimetres and metres. Only containers have capacity. The capacity of a container is the maximum volume of liquid that it can hold. Hence capacity is measured in the same units as liquid volume. Thus, a wine glass may have a capacity to hold 250ml, but the liquid volume of the wine may only be 150ml.

Misconception 2: Conservation of liquid

Children often believe that the amount of liquid has changed when a set amount has been poured from one container to another of a different size. They believe that there is more liquid in the one that has the highest level. 

Misconception 3: Reading Scales 

• some children pick the container up and fail to keep it vertical when reading the scale.
• some children read the scale by looking at the value at the top of the meniscus (curve in the surface of a liquid, produced in response to the surface of the container or another object. It can be either concave or convex) 
• some children read the scale from different heights so that parallax (difference of orientation of an object viewed along two different lines of sight) occurs. Some pupils do not understand the measurement between marked divisions on a scale.

Teachers need to ensure that children have the opportunity to use and read a range of measuring scales on real containers with different scales in different orientations. Encourage children to make sure that they have the container on a flat surface and are looking at the liquid at the same level. They must ensure that they are looking at the base of the meniscus. Encouraging children to estimate liquid volume before measuring will support some of these activities