Teaching Algebra with Manipulatives

Using Overhead Manipulatives
Demonstration 2
Solving Inequalities Using Addition and Subtraction
• Use the transparency you prepared with the
chart on page 320 of the Student Edition to
review the inequality symbols and their
meanings.
2x 3 3x 7
• Display the equation mat transparency.
Across the top of the mat, write 4 less than
twice a number is no more than the number
plus 1. Ask students what inequality symbol
you need? Write the symbol in the center
of the mat by altering the equals sign.
• Model each side of the inequality from the
written form.
• Ask students how to solve the inequality.
Remove a cup from each side; add 4 zero
pairs to the right side; remove 4 negative
counters from each side; the solution is
{xx 5}.
4 less than twice a number is no
more than the number plus one
Algebra 1—Chapter 6
• Check the solution by substituting 5
counters for each cup, then 4, then 6.
Extension
Graphing Solutions to Inequalities
Use the number line transparency to graph
the solutions to the inequalities solved in
Teacher Demonstrations 1 and 2.
10 8 6 4 2 0 2 4 6 8 10
10 8 6 4 2 0 2 4 6 8 10
x 6
x 10
x 5
10 8 6 4 2 0 2 4 6 8 10
© Glencoe/McGraw-Hill 113 Teaching Algebra with Manipulatives