Assign a value to each block color. Assign the value one to red blocks, the value ten to green blocks, and the value 100 to yellow blocks. Write the number "1" using the permanent marker on one side of each of the red blocks. Write the number "10" on each of the green blocks. Write the number "100" on each of the yellow blocks.
Hold up one block from each color for the class. Tell the students the "value" of each block color. Ask them to repeat the value of each color block. Arrange three blocks in order of place value on each student's desk or on a table where all students can see them. Make the abstract concept of place value concrete by using colored blocks to represent value.
Write a number with three place values on the board, such as 125 or 211. Divide the students into teams of 3 students on each team. Instruct one student from each team to select the number of blocks that equal the value in the "ones" place. Ask a second student from each team to select the number of blocks that equal the value in the "tens" place. Have a third student choose the number of blocks from the "hundreds" place to complete representing the three-digit number in blocks. For example, 125 will be represented by five red blocks, two green blocks and one yellow block.