Construct representations for two-digit numbers in the base ten number system.

Grades K-3

**Introduction**

It is believed that the base ten number system was first developed by the Indian culture in the Indus Valley 5000 years ago and that it represented counting on a person's hands. The concept of zero was introduced in the same culture about 1500 years ago. This lesson uses a visual representation to aid in learning the base ten number system.

**Preparation**

Prepare number card assignments to hand out to the students.

**Procedure**

The teacher reviews the concept of base 10 and then give each student a two-digit number on a card or page to create the model in base ten blocks for this number.

The student will use the GollyGee Blocks Grid feature and the Camera 2 function (bird's eye view) to place cubes or other shapes on the grid to represent rods and cubes. The students may also enjoy choosing different colors for the blocks they use in their models, or some textures may apply here also.

Students can use the ABC Text function to write the two-digit number word on the 3D scene and then print out their number creation. Some students may find stacking some objects or shapes a fun and interesting challenge.

**Evaluation**

Teachers are encouraged to use the student printouts for assessment.

The teacher may evaluate student understanding by assessing their work on the monitor while watching them work.

The teacher may have students describe how they did the activity.

The students may be asked to make math journal entries for evaluation.

**Extensions**

The students may trade their printed work and write the number of a friend's picture. These can be displayed on a class bulletin board, or a class book can be created.

A different student picture can be put up on the class monitor screen (or up on the class computer screen) for a day to view and for the class to identify.

The class can play "How high can we go?" and discuss the strategies it would take to determine the highest possible number that can be modeled using the software program.