Bar Model Method

The bar model method

The bar model method (also known as the Singapore bar model, and as a tape diagram or strip diagram in the United States) is a visual strategy for solving arithmetic word problems. Quantities are drawn as rectangular bars to make the relationship between the known and unknown values visible.

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

The model method is built on two base models:

• 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.

Figure: The model method selection screen.

Each base model comes in variants that determine which arithmetic operation the model supports:

• Models with unequal parts for exercises involving addition or subtraction.
• Models with equal parts for exercises involving multiplication or division.
• Models with an unknown number of equal parts for exercises in which the student has to find the number of parts or groups.

Creating a model method exercise

A bar model method exercise in Algebrakit has the following parts:

• The problem statement, which is an arithmetic word problem
• The bar model, to be completed by the student
• The calculation area where students write their calculations.

Figure: Defining the model in the exercise editor.

You define the problem by selecting the desired model out of the six standard options. You also define the labels and values. Leave one value open to indicate the unknown value.

Use the Student selects model checkbox to indicate whether the selected model will be visible when the exercise starts or whether the student must select the correct model from the six options.

You don't have to configure the calculation area; Algebrakit will automatically handle it based on the model you defined.

Answering a model method question

Students choose the correct model if configured.

Figure: Choose a model.

Students complete the model by setting the number of parts or subdivisions, selecting labels, and filling in the values. Next, they write their calculations to solve the problem arithmetically.

Algebrakit evaluates both the model and the calculation for correctness.