Calculator fun

Calculator fun.

Calculators are no substitution for knowing your facts, but sometimes they can be used to make some fun mathematical discoveries.

For grades 1-3

Try multiplying any number by 10.  What do you notice?  Now try multiplying by 100.  Now 1000.  Think you could do it without a calculator now?

Grades 4-5

Same as the younger kids, try multiplying any number by 10 then 100 then 1000.  Seems pretty simple doesn’t it.  You might not need a calculator.  Before you make up a rule though, try multiplying a number like 4.7 by 10, then 100 then 1000.  Now try 2.587. 

Once you feel that you can come up with a rule, try dividing by 10, then 100, then 1000.  Can you figure a rule out for that?

Grades 6-8

Alright, get out you calculator but also paper and pencil.  I’ve got two tricks you might find pretty cool.

Start with a two digit number, like 35 and multiply it by 11.  When you get the answer write it down making the middle number a different color.  Try this several times.  You should start to see a neat pattern forming making it easy to multiply any two digit number by 11 without a calculator.

Now check this out.  Take any two digit number ending in 5, like 45.  Square it (multiply it by itself.)  Write down your answer.  Do this again several times.  What do you notice?  It might take a little while and you may need to ask your parents for some help, but a real nice pattern is there. 

Math Circle Fun

Circle Fun

Grades 1-3

You'll need a ruler for this.  Near the center of a piece of paper make a dot.  Now, measure a distance in any direction from that dot and make another dot.  Do this again measuring the same distance from the original dot now in a different direction.  Keep going back to the same dot and measuring the same distance only in different directions.  When you've done this many times, say at least 10, connect the outer dots.  What if you did this a million times?  What do you think it would form?

Grades 4- 5

Cut a regular piece of paper into strips 3 inches wide.  Roll them up to make 3-inch long tubes less than 2 inches in diameter.  Now, using another piece of paper,  Using either a compass or simply a piece of string, make a circle with radius 1 inch, then 2 inches, then 3 inches and so on.  Cut the circles out to form disks.  Between each disk place a tube and see how high you can build a tower.


Grades 6-8

Using a sewing tape measure, find a something circular in the house.  Measure the distance around the circle.  Now measure the distance across at its widest point (diameter.)  Next take the distance around (this is the circumference) and divide by the diameter.  Record your answer.  Repeat with other circular objects recording your answer each time.  Do you notice something happening?  Anything familiar?

Junk Mail and Mail?

Grades 1-3

Count how many pieces of junk mail make it to the recycling bin each day.  Compare the number of pieces of junk mail to other mail.  Make a big comparison at the end of the week.

Grades 4-5

Junk mail can be pretty heavy.  Keep track of the junk mail that ends up in the recycle bin in your house.  At the end of the week, hold it all while you stand on a bathroom scale.  Then weigh yourself and subtract.  This is how much weight your family recycled in junk mail this week.  Multiply by 52 and you’ll have an idea of how much junk mail comes to your house every year. 

Grades 6-8

Does one day of the week generate more junk mail than the others?  Try setting up a simple line graph for a couple of weeks.  Record the number of pieces that your family receives each day.  Make a prediction for the third week and see what happens.

Measuring up

Grades 1-3

Take a sewing tape measure outside and into the woods.   A fairly loose way to determine the age of a tree without cutting it down and counting rings is to measure the circumference (distance around.)  A tree’s age in years is approximately the same as its circumference in inches.

 

Grades 4-5

Find a can of paint in your house.  Read the label to see how much area can be covered with one can.  Using a tape measure find a part of your house that could be covered by one can of the paint.  Kids, this is a math question.  Please don’t see how much the can will cover by actually painting!

The same could be done with grass seed.  How many bags you will need to seed your whole back yard?

 

Grades 6-8

Ruler Guestimation – Just like guessing a number between 1 and 100 only you are trying to find a number between 1 and 12 on a ruler.  These numbers, however, include all the fractional parts of an inch.  For example, 

The number to find is 6 9/16

Guess: 6

Response: higher

Guess : 7

Response: lower

Guess: 6 ½

Response: higher

Guess: 6 3/8

 

And so on.