Explain what a meter is. Show that a blackboard ruler is exactly one meter long. Take a step and say that this is about one meter. Explain that you can estimate the length of objects by comparing them to one big step. This is because you already know that one big step is about one meter. Show this with help from the blackboard ruler. Have the students estimate the size of different objects in the classroom. After students have given an answer, you can measure the objects to check whose estimate is the closest. Next you show images on the interactive whiteboard. The students must stat whether the length of the objects in real life is about three meters or thirty meters. Put the images in the correct box. Afterwards you show other images and the students must estimate how long the object is in real life. They can choose from a few possible answers. You can also name a number of objects yourself, of which the students must estimate the length.

To check whether students can estimate the length of objects in meters, you can ask the following questions:

- What is about one meter?

- How can you estimate the length of an object?