Daily Science Aug. 24 Describe how you would use a weigh boat to mass a chemical What is a scaled device? What are the three questions you have to ask yourself when using a scaled device? Name the following:

Mechanics of measurement (pg. 9) Science is only as good as the instrument that measures it Use with Physics Skills worksheet Recording Measurements

Accuracy vs. Precision Accuracy- how close you are to the ‘true’ measurement. Precision- how close your measurements are to each other.

How to read a scaled device Step 1: Determine the intervals used on the scale. (Is it counting by tenths, ones, tens, fives, etc.?) Step 2: Record the ‘certain’ measurement. Step 3: Guess and record the uncertain digit. The uncertain digit is in the next tens place over from your interval (if your device is counting by ones, the next place over is the tenths) This is a guess. It is used when the measurement falls in between two lines on your device Recording Measurement Worksheet

How would you read this? 1. What is it counting by? Ones 2. What is the measurement? 15 3. What is the uncertainty number? 15.2 or 15.3

Graduated cylinder Always read the bottom of the meniscus at eye level.

How to use a mass scale Make sure it is on and the lid is UP. Zero the balance before you mass NEVER put chemicals directly on the plate If you spill chemical on it brush it off into a garbage can If you are placing the chemicals in a container (i.e. a beaker or weigh dish): Place the container on the scale and zero it Leave the container on the scale and add your substance

Measurements Lab Place the lab on page in your notebook Put on goggles Collect materials and begin!