Students have repeated experiences breaking one number into two parts or combining two parts to form a whole, and they consider the relationship between the parts. Students work with composing and decomposing numbers to 20 and focus on addition combinations of 10. Students model and solve addition and subtraction problems to clarify and communicate their thinking. Students create their own representations of the data they collect, organizing their data and providing pictures that help describe what the data shows.

They measure relatively small lengths and larger distances to:

• understand that measurement is applied to both objects and distances;
• know where to start and stop measuring;
• know which dimension to measure;
• measure the shortest line from point to point; and
• understand that many measurements are not reported in whole numbers.

Students create, describe, extend and make predictions about repeating patterns, and analyze the structure of repeating patterns by identifying the unit of each pattern. Students also work on carefully observing, describing and comparing 2D and 3D shapes. They explore properties of polygons, including sides, vertices and angles and are introduced to the concepts of congruence and symmetry. In a data unit, students develop a question, collect data, represent the data and describe and interpret the data.