Math Antics - Polygons

Estimate Angles

Estimate angles from sisolica

Types of Angles

Types Of Angles from pprosser

Rounding to add or find the difference

Word Problems : Estimating

In your groups, solve the following word problems.

   Estimate the sum or difference by rounding each number to the nearest ten.

1)      Sam picked 374 lemons and Tim picked 929 lemons from the lemon tree. Estimate how many lemons they both picked ?

2)       Alyssa's Cupcake Shop sold a total of 586 cupcakes today, and 213 of those had sprinkles. Estimate how many cupcakes were sold without sprinkles?

3)       There were 378 scissors in the drawer and Nancy put away 324 more . Estiamte how many scissors are now in the drawer?

Now estimate the sum or difference by rounding each number to the nearest hundred.

4)       John has 678 baseball cards. Benny bought 347 of John's baseball cards. Estimate how many baseball cards  John still owns?

5)       Keith found 935 seashells on the beach and  he gave Melanie 126 of them. Estimate how many seashells  he now has?

6)     Sally and Alyssa decided to bake cookies for the family picnic. Sally baked 611 raisin cookies and Alyssa baked 649 sugar cookies. Estimate how many cookies they baked altogether?

Round to the Nearest Hundred using Rounding Rules

Rounding to the Nearest Ten

How to Estimate.

Before doing the actual calculation you should think:

"How do I go about making this estimate?"

 Different numbers need different methods:

Example:

• 550 + 298: 298 is nearly 300 so an estimate is 550+300 = 850
• 550 + 248: 550+250  = 800

But how do you know what to do? Lots of Practice!

                            Tips and Tricks

Here is a  method you might like to use:

Round the numbers up or down before the calculation.

Example: 206 × 390.

Because 206 is nearly 200, and 390 is nearly 400, the answer will be close to

200 × 400 = 80.000

http://www.mathsisfun.com/numbers/estimation.html

Estimation is a Skill for Life.

As you walk around and live your life, imagine if you could easily estimate:

• how much a bill will be,
• which item is the best value for money
• the size, areas and angles of things

Also, it would be great if you could quickly guess how many people are in a room, how many cars in the street, how many boxes on the shelf, or even how many seagulls on the beach?

We are not talking exact answers here, but answers that are good enough for your life.

                             Exact vs Estimate

In mathematics we often stress getting an exact answer. But in everyday life a few cents here or there are not going to make much difference ... you should focus on the dollars! Estimation is ...... finding a number that is close enough to the right answer. You are not trying to get the exact right answer What you want is something that is good enough (usually in a hurry!)                                            Why?1.Estimation can save you money. Always do a quick estimation of how much you should pay: Example: you want to buy five magazines that cost $1.95 each. When you go to buy them the cost is $12.25. Is that right? "five at $1.95 each is about 5 times 2, or about $10" so $12.25 seems too much!  Ask to have the total checked. 2.Estimation can save you time (when the calculation does not have to be exact) Example: you want to plant a row of flowers. The row is 58.3cm long. The plants should be 6cm apart. How many do you need? "58.3 is nearly 60, and 60 divided by 6 is 10, so 10 plants should be enough." 3. Estimation can save you from making mistakes with your calculator: Example: you are calculating 107 times 56, and the calculator shows this: 952 Is that right? "107 times 56 is a bit more more than 100 times 50, which is 5.000"  Ooops! you must have typed something wrong ... ... in fact you pressed 17×56 (you left out the zero), and without estimating you could have made a really big mistake! Estimation helps you focus on what is really going on. It helps you to check your Math resolutions as well! Estimation helps with your Confidence, Judgement and Decisions! http://www.mathsisfun.com/numbers/estimation-tips-tricks.html

Why is it important to estimate? Kids Video

Estimation vs Rounding

How to draw a climate graph on graph paper

Drawing Line Graphs by Hand

How to make a Climate Graph

Plotting a Graph

This will be graded.

Class activity

On the graph paper, draw a line chart  to illustrate the minimum and maximum temperatures in São Paulo from the  15th   to 24th of February.The temperatures are in Celsius. The information was collected by Caio Peroni from Climatempo.

São Paulo	15th	16th	17th	18th	19th	20th	21st	22nd	23rd	24th
Min.	21°C	21°C	21°C	21°C	20°C	21°C	21°C	21°C	21°C	21°C
Max	30°C	27°C	30°C	30°C	30°C	29°C	31°C	27°C	28°C	29°C

Observations:

1. Plan the graph carefully on the graph paper. Pay attention as to how you use the space.

2. Insert title and labels correctly.Don't forget to show the units and a key.

3. Use a ruler.

4. Present NEAT work.

Plotting Graphs

1. Homework activity.

On the graph paper, draw a line chart to illustrate the temperaturas in São Paulo and Miami, 19th to 28th of January 2015.The temperatures are in Celsius and are only an estimate.

City	19 th	20 th	21 st	22 nd	23 th	24 th	25 th	26 th	27 th	28th
São Paulo	25°C	25°C	30°C	35°C	30°C	35°C	35°C	30°C	25°C	25°C
Miami	20°C	20°C	15°C	20°C	25°C	20°C	15°C	15°C	20°C	20°C

Observations:

1. Plan the graph carefully on the graph paper. Pay attention as to how you use the space.

2. Insert title and labels correctly.Don't forget to show the units and a key.

3. Use a ruler.

4. Present NEAT work.