Unifix cubes are an ideal way to model addition and subtraction problem scenarios. When put together, they stay together, unlike sets of Base 10 Blocks or other discrete manipulatives, so they preserve the addends – one addend is red, the other blue, and they remain so. They make the Part-Part-Whole relationship visible. And Unifix cubes can be easily handled, put together, and taken apart by small fingers.
These pages include number lines on which students place numbers of cubes to match the problem being discussed. They then add to the number, take away from it, or count up from it, depending on whether they have two parts (addition), or one part and the total (missing addend).
The big advantage in using Unifix cubes on a number line is the ease with which students can model “missing addend” problems, which can be solved either through counting on (addition) to the known total, or subtracting from the known total to find the unknown addend, or part.
These pages include: (1) number line templates sized for letter (0-10), legal (0-18), and 11 by 17-inch (0-20) paper; (2) a set of word problems corresponding to 7 different problem types enumerated in the Common Core; (3) student assignment pages for addition, subtraction, and missing addend problems on which students can write the particular problems assigned; and (4) a complete set of notes on the use of these number lines.
Common Core Standards:
K.OA.1: Represent addition and subtraction with objects…, expressions, or equations.
K.OA.2: Solve addition and subtraction word problems, and add and subtract
within 10, e.g., by using objects or drawings to represent the problem.
K.OA.3: Decompose numbers less than or equal to 10 into pairs in more
than one way, e.g., by using objects or drawings, and record each
decomposition by a drawing or equation (e.g., 5 = 2 + 3 and 5 = 4 + 1).
K.OA.4 For any number from 1 to 9, find the number that makes 10 when
added to the given number, e.g., by using objects or drawings, and
record the answer with a drawing or equation.
1.OA.1: “Use addition and subtraction within 20 to solve word problems involving situations of adding to, taking from, putting together, taking apart, and comparing, with unknowns in all positions…”
Subjects: Math, Basic Operations, Word Problems
Level: Grades K-1
Duration: Open – could be used for weeks.
Answer Key: None needed
A Smartboard 14 file is also included which includes cloned Unifix cubes of all colors to be placed inside the number lines.