• Invite a child to roll out a floor mat and explain that you would like to present the Broad Stair.
  
• Walk with the child to where the Broad Stair is kept, and show the her how to hold one of the prisms by using both hands, with one hand at each end of the prism.
  
• Carry each prism separately and scatter them on the mat.
  
• Find the broadest prism (by comparing it to the others), and place it in the corner of the mat closest to the child.
  
• Select the next broadest prism, and place it beside the first.
  
• Continue building the Broad Stair.
  
• When you are finished show the child how the thinnest prism acts as the "control of error" by fitting flush at the step of each stair.
  
• Scatter the prisms and invite the child to repeat the presentation.

• Invite a child to build the Broad Stair.
  
• Ask the child to close his eyes, while you remove one of the prisms.
  
• Leave the prism in full view of the child.
  
• Ask the child to show you where the prism belongs in the Stair.
  
• Place it where he has indicated.
  
• The child should confirm his analysis with the smallest prism.

• Repeat Extension 1, except this time hide the prism that you remove behind you.

• Ask the child to scatter the prisms on a mat across the classroom and then build the Broad Stair.

• The child scatters the prisms around the classroom and builds the Broad Stair on a mat.

• As a parallel activity, encourage the child to construct the Pink Tower and the Broad Stair horizontally. Allow the child to compare and contrast the two items.

• As Extension 5, except built vertically.

• Build the Pink Tower as it is shown in the picture, then starting at the top carefully remove each Pink cube.

• Known as the "Shadow". Build the Pink Tower and Broad Stair as it is shown in the picture, then shine a bright light at the Pink Tower, creating its shadow over the Broad Stair.

• Muscular development.

• Thick - thin.
  
• Thicker - thinner.
  
• Thickest - thinnest.

Extension 7