Modelling place value with decimal numbers

Hello, my math friends!

I wanted to share something I put together not long ago to support students in understanding the value of the digits when we write decimal numbers.  These decimal “tents” as I call them, are made from card stock and are folded in half to form a tent shape.  Each one is cut so that the decimals on each card line up one under the other – but the digits themselves are still visible.  It’s a bit hard to explain, I fear, but the following pictures should help…

This is what the cards look like, folded.  I like to put a strip of magnetic tape on the back of each one so that I can stick them on the board, matching them to a model to show the same amount.


The cards are trimmed so that the decimal point falls at the same location on each of the “expanded” decimal number.  On the decimal tents line master, this means you’ll slice off the light grey zeroes…


So when the cards are overlapped, the decimal number itself is clear, and made up of the parts.


It’s a powerful tool to use with students.  Helping them to see that we can decompose a decimal number in the same way we do whole numbers is an important connection!  This decimal tent set shows that 3 + 0.6 + 0.08 = 3.68.

Imagine a series of these tents strung along a string or wire in your classroom.  Have students create a 3 digit decimal number, model it with materials and then order that number along the number line (that is, to hang their cards right on the wire!) placing it relative to the others.  It’s a neat way to compare and order decimal numbers!



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