Real Life Inequalities.

  I decided it was time to have my students do  bit of the work so in Algebra I, I began one variable inequalities by having students find real life examples and write them on the board.

We run into them all the time but we don't connect the situations with being inequalities.  One such situation deals with posted speed limits.  You can go as fast as you want up to that speed but not over it or you might receive a ticket.

Another two situations involve credit cards.  The first is with the credit limit.  A person can charge up to that amount but no more so the inequality might read x < $10,000.  The other inequality is in regard to the minimum payment.  That is the least amount a person can pay but they are welcome to pay more.  The equation might look like x > $122.30. 

Twitter uses an inequality when they restrict messages to 140 characters while many contact forms might restrict the message to 500 characters.  Then there is the issue of fundraising.  Most groups set a minimum amount they hope to raise through selling candy, cookies, or a raffle.  Although they hope for minimum amount, they will not stop there.  Instead, they will continue accepting donations.

There are some jobs out there which require you to sell a minimum amount in order to receive additional funds.  It might be you must sell over $8000 worth of computers before you get a bonus.  This would be another real life example of an inequality. 

In addition, there are other examples such as elevators which have a maximum weight load usually couched as a maximum load of 9 people or 1000 pounds.  Check the bridge signs and they might say have a restriction on maximum truck weight or a height restriction so a vehicle must be under 7 feet off the ground.

There is also the minimum travel time listed when driving or flying.  Out here the minimum is 45 minutes from Bethel to the village if everything is great and you get the fast plane but it could take 2.5 hours if you end up going to the two other villages first.

Sometimes, when we find something we want to buy that special pair of shoes, or dress and we have to plan the amount of money we need to save each week.  Or when you buy a house or a car, you have a minimum payment to make each month.  My mother always said that if you pay $100 extra each month, you'll pay your mortgage off much sooner.  I've always kept that in mind.

So many different possibilities, all provided by my students the other day.  It allowed them to find the real life applications before we began studying the topic so they can build a solid foundation.  Later in the week, I'm going to give them an inequality and they will have to write the situation to go with it.  I'll let you know how that goes.

Let me know what you think.  I'd love to hear.