Lesson objective: Understand what it means to compare two groups of objects by building cube towers that have the same and different quantities. Extend understanding that we can use math comparison language, *greater than*, *l**ess than,* and *equal to,* when comparing two groups to one another.

Students bring prior knowledge of comparing from K.MD.1 and K.MD.2 in Unit 8. In these standards students compared measurable attributes to see which has more or less of the attribute. This prior knowledge is extended to comparing groups of objects or sets and using the comparison language *greater than*, *less than,* and *equal to*. A conceptual challenge students may encounter is fully understanding the meaning of the comparison language and using it to describe the work they are doing. Students may find it easier to understand the comparison words, more and greater, since we more commonly say, “Who has more?" *Less,* *less than, fewer,* and *equal, *are less familiar vocabulary to many young students. Modeling with math tools while using the comparison language will help students to develop an understanding of this new terminology.

The concept is developed through work with building blocks or connecting cubes, which helps students see the quantity in each group in order to compare the groups using counting and matching strategies.

This work helps students deepen their understanding of equivalence because students are making a connection between numbers and the quantities they represent. This lesson sets the foundation for understanding what equivalence means. Students engage in Mathematical Practice 2 (Reason abstractly and quantitatively) as they practice working with concrete objects and the numerals they represent. Students will practice using comparison language as they build towers have various quantities. Students may use counting, matching, and visual cues, to help them compare.

During the task solution encourage students to share the towers they made as you model the comparison phrases.

- Model
*equal*, *equal to* by holding up a tower and asking, "How many cubes are in my tower? Do you have a tower that is the same? Can you make a tower with the same number? What strategies could we use to make sure our towers have the same amount?"
- Model
*greater *and *greater than *by holding up a tower and asking, "How many cubes are in my tower? Can you make a tower that has a number of cubes that is has more than mine? Your cubes are *greater than* my cubes."
- Model
*less* and *less than* by showing two towers and counting both of them. Ask, "What do the notice about the towers? This tower that is shorter has fewer cubes. We can say that this number of cubes is *less than* this number of cubes."

Observe and look for ways students find cube towers that are the same and different. These are strategies they may use:

- counting the cubes in each tower
- lining them up or matching them
- looking for visual cues

**Key vocabulary:**

- compare, comparison
- equal, equal to
- greater, greater than
- less, less than
- more
- same

**Special materials needed:**

- connecting cubes
- connecting cubes, dot cubes, and game directions (for additional practice activity)