SCIENCE SKILLS: SPREADSHEETS & SIG FIGSummer work for incoming AP/H science students

Why learn a spreadsheet?

Scientific inquiry generates data…and with the advent of computers, lots and lots of data. In turn, computer programs are used to compile and statistically analyze that data. Excel is a spreadsheet program used in academic and industry labs for organization, calculation, and presentation of data.

Excel is the spreadsheet program included in the Microsoft Office suite. There are also free spreadsheet programs in Google Drive and LibreOffice.

Tech Requirements

This tutorial references a Mac running OS X (10.6.8) and MS Office (Excel) 2011

If you use a PC, a different version of Office, Google Sheets, or LibreOffice some details will be different than those of this tutorial Look for command synonyms, different button

locations, etc. Search the web for a tutorial your specific

hard/software if it is very different than this.

• Copy a string of data from any source (MLB.com, bls.gov, ncdc.noaa.gov, etc)• Highlight a spreadsheet cell; paste the data in.

If it all pastes into one cell, go up to the ‘data’ drop down menu and choose ‘text to columns’ to separate in cells.

Build a Data Table

• Repeat so you have a few sets of data in a table format

• Title each row with an independent variable; each column with a dependent variable.

• Highlight all the cells; use the ‘borders’ button to add grid lines

• Highlight the table; under ‘charts’ choose ’column’.

You can drag the graph around by the border

Graphed Data

• Choose a chart layout and type in title, axes labels

• Formulas start with the equal sign. Use math order of operations.

• The SUM command is used to total a column or row. Write a formula, as above, or highlight the data to sum, and clickΣ.

Formulas for Calculations

Put the cursor in the bottom right of the cell so that it changes to a +; hold and drag right to repeat the sum command in all the rows

+

Copying Formulas to Other Cells

• Use the ‘decrease decimal’ button to round (see slides 16 – 20 to follow the rules for this).

Under View, check the ribbon and formula bar to make it easier to find tools/see your cell entries

As You Work

Wrap text makes all your text visible

Merge is useful for centering a title on your sheet, etc

With Number you choose the format of your data

Worksheet Displays

• Insert additional rows and columns the number you highlight is the number that will be inserted

• Graph only select columns of data from the table

• Write and use other formulas i.e percent change = (((final – initial)/initial)*100) Use the formula builder button for a list of commands

Completely flummoxed? Ask your parents – they may very well use Excel in their jobs.

Try This

Significant Figures

When reporting scientific data, ‘sig fig’ tell the reader the degree of accuracy of the measured data.

Measurements are accurate only to the intervals given on the scale. If the object falls between 2 points on a scale, any value between those two points is, at best, an estimate.

Example: The length of a pin is between 2.8cm and 2.9cm. You estimate it to be 2.85cm; your lab partner estimates it at 2.83cm. However, neither of you knows it’s length to the hundredth's place. Therefore, the first 2 digits are CERTAIN numbers of measurement & the 3rd is an UNCERTAIN number. Only CERTAIN numbers are reported; they are the ‘significant figures’.

Rules

Non-zero integers always count;1457 has 4 sig figs, 236 has 3 sig figs.

Zeros, three classes: leading don't count; 0.0025 has 2 sig figs captive count;1.008 has 4 sig figs trailing only count with a decimal point; 100 has 1 sig fig,100.0 has 3 sig figs

Rounding off

If less than a 5 round down, if equal or greater than 5 round up.

In a series of calculations carry the extra digits through to the end then round off.

Round off to the correct number of sig figs: 4.348 to 2 sig figs is 4.3

Multiplication & Division:

The number of sig figs is the same as the measurement with the smallest number (this is a limiting number)

4.56 x 1.4 = 6.384 = 6.4 3 sig figs 2 sig figs round to 2 sig

figs

8.315/298 = 0.0279027 = 0.0279 or 2.79 x10-2

4 s.f. 3 s.f. 3 sig figs

Addition & Subtraction:

The limiting number is the number with the smallest amount of decimal places.

12.11+ 18.0 + 1.013 = 31.123 = 31.1 the 18.0 is limiting as it only has 1 decimal

place,so round off to 1 decimal place

0.6875 – 0.1 = 0.5875 = 0.6 the 0.1 is limiting so round off to 1 decimal

place.

Practice

Do some calculations and practice rounding given sig fig. Check your work using this online calculator

Other Topics to Review

Scientific methods Independent vs dependant variables

Metric units Dimensional Analysis (converting between

units); Exponential notation

Atomic structure bonding

Polarity of water Resulting properties