Grade Levels: K-3

This page provides information to support educators and families in teaching K-3 students about ounces, pounds, and tons. It is designed to complement the Ounces, Pounds, and Tons topic page on BrainPOP Jr.

In early elementary education, children explore the units, systems, and processes of measurement. We recommend giving your children plenty of hands-on practice to help them recognize the attributes of length, weight, volume, area, and time. Hands-on activities will also help them recognize and select the appropriate unit and tool for measurement and build and improve their measuring skills. This movie explores weight through ounces, pounds, and tons. Measurements within the metric system will be addressed in separate movies.

Review with your children that weight is how heavy something is. Weight is a measurement of the gravitational force acting on an object. Mass, however, is a measurement of the quantity of matter in an object. Therefore, the weight of an object changes based on gravitational pull, while its mass remains the same. An object on the Moon will weigh less than the same object on Earth because there is less gravitational pull. However, its mass on the Moon will be the same as on Earth. The distinction between weight and mass is important in the physical sciences and laying the basic groundwork for this concept can offer an opportunity to make a connection to science.

Children can estimate the weight of different objects to find ones that are heavier, lighter, or about the same weight. Remind your children that when they estimate, they make a good guess. They can also use a balance scale to compare weights of objects. You may wish to model key phrases such as “heavier than” and “lighter than” or “weighs more” and “weighs less.”

It takes time and experience for young students to understand the need for standard units of measurement. A good way to introduce students to the need for standard units is through exploration of balance scales without unit measurements. Ask your class to look at and feel objects and predict which is heavier or lighter. Ask them how they could prove which is heavier or lighter. Then, compare the objects on opposite pans on a balance scale. Give your students many opportunities to predict which objects are heavier and lighter and then check their predictions on balance scales themselves. Then ask students to find a way to find objects that weigh the exact same amount. Finally, students can use a single unit of weight to compare the weights of various objects to prove that they weigh the same amount. For example, you might ask the class to use pennies or cubes to find the “exact” weight of classroom objects. After you have established the need for a common unit of measurement of weight, you can begin to discuss the standard measures of ounces, pounds, and tons.

In the United States and a few other countries, we often use ounces, pounds, and tons to measure weight. Show your class a scale with ounces and pounds and have your children look at the numbers and how they are organized. They may have difficulty determining the difference between the ounce and pound marks, so be sure to give the class time to explore the scales up close. Show an object that weighs about an ounce, such as a slice of bread. Have your children find other objects that weigh about an ounce. Remind them that they should use ounces to measure light objects. The abbreviation for ounce is “oz”. They should use pounds to measure heavier objects. Show an object that weighs about a pound, such as a loaf of bread or a small melon. There are 16 ounces in 1 pound. The abbreviation for pound is “lb” and the abbreviation for pounds is “lbs.” Weigh different objects together on a scale and have your children practice reading the measurements.

Explain to your children that people can use tons to measure very heavy objects. There are 2,000 pounds in a ton. A small car weighs about 1 ton. The largest mammal is the blue whale, which can weigh about 150 tons, or about 300,000 pounds. Compare that weight to an elephant’s, which is only about 15,000 pounds.

When children learn about measurement, they develop the fundamental concepts and skills they need to explore the world around them. Measurement tools help them understand the need for standardized units. What if everyone used rulers with different units? What might happen? Math and measurement pose fascinating questions about our world and provides answers as well.