Encourage students to make observations about the two groups. Listen for references to relative numbers of objects. Students continue to add to the collection. Encourage them to predict which group an object will belong to based on observations of the characteristics of the objects in each group. Partners take turns using the balance scale to compare the masses of two objects.
Partners work together to order three objects according to their masses.
The teacher listens for language such as greater than, less than, equal to, in between, etc. Students order a set of six or more objects according to their masses. Encourage them to try different strategies, such as comparing everything to say, two-color counters. Students work in small groups or all together in a large group. Students use the vocabulary to describe the objects as they place them in each set.