Subtract With Circle Models uses circles to demonstrate subtraction of fractions.
You can input the minuend and subtrahend for a subtraction of fractions example. The minuend must be less than 7 and larger than the subtrahend.
Press the <OK> button and the circles for the minuend, subtrahend and the difference number lines will appear.
Uncheck the <EXPLAIN> check box to turn off the answer and the explanation. You can ask your students to complete the number sentence.
Uncheck the <SHOW INPUT> check box to make the input dialog boxes work like a password input boxes, hiding the numbers you input. With <EXPLAIN> and <SHOW INPUT> unchecked you can ask your students to write a number sentence that explains the picture.
With <EXPLAIN> and <SHOW COLOR> unchecked you can ask your students to complete the picture by shading the number lines.
Start with a common denominator such as 3 3/4 and 2 1/4. You can arrive at the difference by removing subtrahend amounts from the minuend.
Then enter 3 3/4 and 2 1/2 to see how the common denominator of 4 is used. If you continue to decrease the size of the subtrahend by fourths from 2 1/2 and then to 2 1/4 etc., you will notice the difference increasing.
Enter 3 0/1 for the minuend and 2 2/3 for the subtrahend. Notice that the minuend has been renamed to 2 3/3 to subtract. Decreasing the whole number in 3 by one will give you 2 3/3, allowing you to subtract the whole numbers and the numerators.
Try 3 1/3 minus 2 2/3. Notice that the minuend has been renamed to allow you to subtract the numerators.
If the minuend numerator is smaller than the subtrahend numerator, the example will show how to borrow. Make sure that denominators are the same if you want to demonstrate an example like 3 - 1 3/ 4. To do this enter 3 0/4 - 1 3/4.
You may copy the screen by pressing <Print Screen> on the keyboard. This copies the screen into Windows Clipboard™. The screen can then be pasted into Windows Paint™ or your favorite imaging program. Windows Paint™ will allow you to select any part of the image to be printed or saved,
Windows 7 users can use the Snipping Tool™ to capture any part of the screen you wish. These images can be edited and saved in PNG, GIF(recommended) or JPEG formats.