There are many different scenarios which students need to recognize and apply the correct operation to. The Common Core Standards list 12 different problem types, some with sub-types. All these scenarios need to be presented to first graders, and all need to be “mastered” by the end of second grade.
Unifix cubes are an ideal way to do this. When put together, they stay together, unlike sets of Base 10 Blocks or other discrete manipulatives. 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, or one part and the total.
Just as important are the questions with which teachers can help students reason out and verbalize which numbers they know, which they don’t know, and how to find that unknown. Question formats are included for each problem type and others are suggested in the notes.
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, legal, and 11 by 17-inch paper; (2) a set of approximately 10 word problems corresponding to 7 different problem types (and referenced to the Common Core types); (3) a “picture” of a question-response student page along with an image of the Unifix cube model on the number line for that particular problem type; and (4) a complete set of notes on the rationale and use of these number lines.
Common Core Standards:
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…”
4.OA.1: “Understand subtaction as an unknown-addend problem.”
5.OA.1: “Relate counting to addition and subtraction…”
Subjects: Math, Basic Operations, Word Problems
Level: Grades K-2
Length: 44 pages in all, many problems, can be used across grade levels
Answer Key: NA
A Smartboard 10 file is also included. Click on the .zip file icon, and you can open the PDF, Word, and Smartboard files separately.