Technology objective: Students will use the TI-81 calculator to "test" whether given values will make an inequality true or false.
Lesson: After a brief introduction to inequalities, students may need some reinforcement when it comes to a problem like this:
Is the following true or false? 5k + 10 < 20, if k = 2
Have students work the problem out by hand or mentally. However, many students get confused when they see "20 < 20." Many will have a tendency to say true. Have the class "test" that inequality in the calculator. The steps are the same as testing an equation. However, instead of an "equal" sign, they will need to enter the "less than" sign. After the inequality is in the calculator, discuss why the students got a false response. Can they find another inequality that would have given a true response? Give them time to find a true response by creating a true inequality.
Assignment: Have the students reflect in their journals about four real-life situations where we use inequality signs. For example, to ride certain rides at Six Flags, you have to be 48" or taller.