## Kindergarten Mathematics Module 3, Topic B

In Topic A, students compared length and height of different objects when their endpoints were aligned and not aligned. Topic B continues with informal comparison of length with students comparing the lengths and heights of linking cube sticks within 10 with a color change at 5. In Lesson 4, to reinforce the importance of the 5-group, they compare multi-unit linking cube sticks to a 5-stick. “My 4-stick is shorter than my 5-stick.” In Lesson 5, they compare lengths with endpoints that are aligned and not aligned. “My 7-stick is longer than my 4-stick. When I push my 4-stick up or turn it on an angle, it is still shorter than my 7-stick.” In Lesson 6, students compare their linking cube sticks to objects. “My 4-stick is shorter than my pencil. My 4-stick is longer than my eraser.” Using linking cubes to directly compare different objects is a precursor to being able to compare the length of two objects using a third object, as well as being able to order the lengths of different objects in later grades, and gives students a practical context for solidifying their developing number sense. In Lesson 7, the students break their 5-stick into two parts. “I broke my 5-stick into two parts. My 5-stick is longer than my 3- or 2-sticks. Together my 3- and 2-sticks are the same as my 5-stick.” This is an extension of their decomposition work from Module 1. This provides the foundation for the number work coming in Module 4 wherein they decompose all numbers to 10. This also encourages their fluency with facts to 5.