Quick Review of the 10’s places 123,456 1’s place 10’s place 100’s place 1,000’s place 10,000’s place 100,000’s place

Quick Review of the 10’s places th s place 100 th s place 1,000 th s place 10,000 th s place

HOW TO MEASURE IN SCIENCE The measurement you make depends on the instrument The the more precise the instrument, the more precise the measurement and more SIG FIGS 10 cm 20 cm 10 cm 20 cm Which ruler is more precise????

HOW TO MEASURE IN SCIENCE The first rule of measuring, you always guess ONCE 10 cm 20 cm 0 cm But how? Look at the increments (lines), you know that the object is between 10 and 20 cm. OBJECT

10 cm 20 cm 0 cm OBJECT YOU KNOW the object is: 1 cm A good guess would be 16 cm or 17 cm or 18 cm. guess goes here (notice that the guess is one 10’s place smaller than the increments)

200 cm 300 cm 100 cm OBJECT YOU KNOW the object is: Good answers are 220, 230, 240 guess goes here (notice that the guess is one 10’s place smaller than the increments) Pay attention to scale 2 cm

200 cm 300 cm 100 cm OBJECT Remember from before, how do we know the 3 is the guess digit? Pay attention to scale 230 cm

200 cm 300 cm 100 cm OBJECT (notice that the guess is one 10’s place smaller than the increments) Pay attention to scale 230 cm = good 23 cm = bad 235 cm = bad WHY?

10 cm 20 cm 0 cm A good measurement would be: Which digit is my guess What place is it in? 1 cm or 2 cm or 3 cm.

10 cm 20 cm 0 cm is 2.1 cm, OK? is 2.0 cm, OK? 2 cm is good?

20 cm 30 cm 10 cm OBJECT Let’s use the more precise ruler What do we know?? Now let’s guess. A quick trick is to look the smallest lines and decide what 10’s place is changing. Your guess will be a 10’s place smaller. ALWAYS 23 cm 23.6 cm

YOU TRY 200 cm 300 cm 100 cm OBJECT 200 cm 300 cm 100 cm Find the 10’s place changing between the smallest increments and make sure your guess is a 10’s place smaller (to the right) OBJECT 180 cm, 190 cm 182 cm, 183 cm, etc…

2 cm and 2.0 cm are not the same in SCIENCE 10 cm0 cm 10 cm 2 cm means: About 1,2, or 3 cm The last SIG FIG in a measurement is always assumed to be a guess 2.0 cm means: About 1.9, 2.0, or 2.1 cm

Even in a digital scale, there is a guess.

If the object happens to line up “exactly” with an increment, you will have to add zeroes to make sure the guess is in the right place. 200 cm 300 cm 100 cm OBJECT 178 cm 200 cm 300 cm 100 cm OBJECT 180 cm 200 cm 300 cm 100 cm OBJECT 200 cm

Which ruler would be read correctly 42 cm 100 cm0 cm 100 cm 40 cm50 cm 40 cm 42 cm 42.0 cm

0 cm1 cm 0 cm 1 cm 0 cm1 cm Some harder ones... Look at the place changing in the smallest increment cm,.53 cm etc….03 cm,.04 cm etc….30 cm (or.29 or.31)

All Instruments are read this way. Even if they look different. They are read with one estimated digit Liquid instrument like graduated cylinders are read at the bottom of the meniscus 10 mL 20 mL What would be a good reading?? Don’t forget the unit. Some have numbers that increase from the bottom up. They tell you how much liquid is in them. 0 mL

Some have numbers that increase from the top down. They tell you how much liquid you have taken from them. 10 mL 0 mL 20 mL 10 mL 0 mL 20 mL StartEnd

1 L 0 L 10 dL 20 dL 0 dL 30 cm 3 20 cm 3 40 cm 3

g g g 9 Triple Beam Balance Just add up the values for each pointer The most precise increments are changing by 10 th s or.1 g So your guess will be a 10’s place smaller 100 th s or.0X g A good reading would be: g g Centigram balance

g g g 9 Triple Beam Balance g 2.56 g

g g g 9 Triple Beam Balance g 1.50 g

g g g 9 Triple Beam Balance g 4.00 g

g g g 9 Triple Beam Balance g 0.04 g The guess is always in the 100th place!!!

The 100 m dash records for the last century. Why did the vertical lines get smaller?