Explain the size of measurements to your child by comparing them to objects they can visualize. For example, one inch is a bottle cap and one foot is the size of a hammer. Then, explain that one yard is the width of a door. Then, go through worksheets, circling the best estimates for each object's length.
This worksheet will help your child learn how to read a ruler using both centimeters and inches. It's an important skill that will benefit them throughout life! With practice, they'll gain a better understanding of these basic units of measurement.
Get a pencil and show your child how wide 1 cm is (about the same width). Then, take a baseball bat and explain that 1 meter is around its entire length. Now your child has an idea of what to picture when hearing cm and m. Look through the worksheet together and show them each object. Ask if the object is likely or unlikely to be the length described.