Form a human number line by telling students to line up and assigning them consecutive integers, with zero near the middle of the line. Write a linear inequality -- an inequality in one variable -- on the board. Tell the students to calculate whether the inequality is true when the variable equals their numbers. Students who are a solution should remain standing while those who are not crouch down, resulting in a visualization of the inequality. Point out that the arrow on a number line matches the standing students.
Create a large coordinate plane on the ground out of masking tape strips -- after making sure the tape won't damage the surface. Use string or yardsticks to represent the boundary of a certain inequality on the grid, then let students take turns tossing a beanbag onto it. Have each student calculate whether the inequality is true at the point where her beanbag lands. Mark each spot with a sticky note marked "X" if it is not a solution and "O" if it is. Help students notice that all solutions are on one side of the boundary.
Have students stand in a rectangular grid pattern, with each student's position corresponding to one ordered pair of integers. Write an inequality on the board. Students whose ordered pairs are a solution to the inequality should raise their hands. Students on the boundary should point toward the part of the "graph" that solves the inequality; students who are not on a solution crouch down. Work together to solve each inequality faster than the one before.
On a simple coordinate plane, graph a simple inequality, then mark a point outside its solution. Challenge students to change one integer or operator in the inequality to make it include the point, then mark a new point and repeat the challenge. One possibility is to divide the students into teams and award one point for each successful modification. To increase the challenge, start marking two or more points for students to encompass with a new inequality. Over time, this activity should help students gain an intuitive grasp of how the numbers and operators in an inequality relate to the shape of its graph.