Bar Model Method

The bar model method

The bar model method is a tool to visualise arithmetic word problems. You can use it as a support for arithmetic word problems, to help bridge the gap between the story in the word problem and the equation students need to solve. When students visualise the individual elements of a word problem, they learn to translate the word problem into an arithmetic problem effectively.

A typical finished bar model method exercise will look something like the following:

• A word problem: "Alice and Bob are selling apples. Alice sold 20. Bob sold 4 fewer than Alice. How many did Bob sell?"
• The model, filled out by the student.
• A solution to the arithmetic problem.

Figure: An example of a finished bar model method exercise.

Authoring a model

The first step to author a bar model method exercise is choosing a model. There are six models available. Models vary in several ways.

Figure: The model method selection screen.

• Part-whole models, where the arrow above the model represents the total, and the individual blocks represent smaller parts.
• Comparison models, where the block at the top represents a larger quantity, and the block on the bottom represents a smaller quantity.

Models also differ in whether their parts are equal or unequal in size.

• You typically use models with non-equal parts for exercises involving addition or subtraction.
• You typically use models with equal parts for exercises involving multiplication or division.
• You typically use models with an unknown number of equal parts for division exercises where a student has to find the number of parts or groups.

Then, fill out the model. Labels are required, and each model must have exactly one unknown value. Algebrakit will automatically generate the arithmetic exercise corresponding to a given model.

Completing a model method exercise

To complete a model method exercise, a student must choose the model they want to use to solve the exercise. You can toggle whether a student can select the model on or off.

The student can complete several sub-tasks in the model method exercise. A student can change the number of parts or subdivisions in a model, pick a label, and fill in the value belonging to arrows. A student then has to complete the problem arithmetically on the lines below the model.

Algebrakit considers a model method exercise finished if:

• The student has found the correct answer arithmetically.
• The student has chosen the appropriate model for the exercise.
• The model does not contain any mistakes.