Lab 1: Introduction

Metric System

Prefixes (to put in front of basic units):

k = kilo = 1000 x c = centi = 1/100 of (which is 10-2 of) m = milli = 1/1000 of (which is 10-3 of) ( = micro = 1/1,000,000 of (which is 10-6 of) n = nano = 1/1,000,000,000 of (which is 10-9 of)

(d = deci = 1/10 of )

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(Note: The way to read the numbers above, for example, is: There are 1000 nm in one (m. There are 1000 (m in one mm.. etc.)

To convert from one metric unit to a different metric unit (a different prefix):

1. First, decide how many places to move the decimal point (the number of 0’s in the chart above indicates the number of places to move the decimal point).

2. Next you need to decide whether to move the decimal point left or right. To decide this, think about which is the smaller unit. (The smaller the unit is, the more of them you need to get the same amount. e.g. pennies vs. dollars)

NOTE: Here is another way to write the conversions, using distance (the meter is the basic unit for distance) as an example:

0.001 km = 1 m = 10 dm = 100 cm = 1000 mm = 1,000,000 (m = 1,000,000,000 nm

The “staircase” method: One more way to remember about sliding decimal points when converting between prefixes in the metric system!

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Move the decimal point 3 places for every step you move on the “staircase”, and in the same direction traveled on the staircase (left vs. right).

Unfortunately, you can see that the “c” prefix doesn’t fit in this pattern, since it would be only 1/3 step above the “m” prefix (e.g. to go from mm to cm you would only slide the decimal point one place instead of 3 places)

Using “conversion fractions” to convert between metric and English systems

When converting from one metric unit to another, you can slide the decimal point as explained above, or you can multiply by an appropriate conversion factor. For example:

2.5 m X 1000 mm = 2,500 mm 1 m

NOTE: Using conversion factors to cancel units is useful in a lot of situations, including if one has to switch from English to metric measuring systems (or vice versa).

For example, in the “Measurement Conversions” table at the front of your lab manual you see that 1 kg is the same as 2.21 pounds (lb). Thus, to convert between kg and pounds, you need to use the ratio of 1 kg/2.21 lb, or 2.21 lb/1 kg. You choose which goes in the numerator and which in the denominator depending on which units you want to cancel out. Thus:

1.3 lb x 1 kg = 1.3 kg = 0.59 kg 2.21 lb 2.21

In general: # to be converted x conversion fraction = answer (with original units) (# with new units)

Graphing Rules

- Check all the graphing rules described in your lab manual (pp. 15-18).
- Label the axes (don’t forget units). Each bar in a bar chart needs a label, but the “x-axis” as a whole also needs a general label that is relevant to all the bars.
- Give your graph a figure number and an informative (“stand alone”) figure caption (~ title).
- If you make a graph by hand: - Do hand graphs in pencil so mistakes can be erased. - If you are making a graph by hand, don’t forget to actually draw in the axes, using a ruler, and also use a ruler to draw bars neatly. - Put “tick marks” on the axes beside each number. Remember, each interval between tick marks must be worth the same amount for a given axis. - For hand graphs, do NOT use the grids provided in the lab manual (e.g. do NOT use the grid on p. 17 or p. 18). Instead, use the squared paper in the lab manual at the end of each unit for graphing (e.g. pp. 29-31). - Note that your graph’s origin does not always have to start with zero, but you MUST indicate what the starting value is for any axis. - Make a nice, large graph, if possible (but keep the axes easy to read).

Tables

- Information about constructing tables is given in your lab manual on pp. 14-15.
- Note that a summary table usually provides information about average values for each group in a column, and the number of replicates involved in another column, rather than listing each “raw data” point separately. (The “replication” or “sample size” column usually precedes the column for averages.)
- Remember to give each table a table number and an informative (“stand alone”) table caption (“title”).
- Tables should always be typed, with lines demarcating the rows and columns.
- Record averages to ONE decimal place MORE than the raw data had (unless you are told otherwise). Record the same number of decimal places for everything of the same kind of measurement (e.g. if other values are given to one decimal place, then a value of 23.0 should be recorded as “23.0”, not just “23”).

Scientific Method = using observations of the external world to figure things out.

For experimental inquiry (idealized): observations (data) ( (produce questions) ( hypothesis ( (specific predictions)( test (via observation, experimentation, which produces new data) ( conclusions (did the data support the hypothesis?) ( (publication of results is useful)

Typical parts of a scientific paper (publication):

- Abstract (overall summary of paper)
- Introduction (general information)
- Materials and Methods (procedures used)
- Results (data/observations presented in tables and graphs, with statistical test results, brief summarizing statements referring to graphs and tables)
- Discussion: conclusions regarding results: comparison of actual results with expected (hypothesized) results (do data results support the hypotheses, and if not then why not?), what do the results MEAN?, explanations, speculations, comments about any potential problems involving study and suggested improvements, comparison with other studies in the literature, clear overall concluding/summarizing statement(s). Note that you do NOT put details of procedures in the discussion section.
- (acknowledgements)
- References or “literature cited” (essential to cite other papers of scientific studies that you have referred to)

Note: Lab reports (discussions, etc.) handed in for this class must be typed double-spaced. Feel free to show graphs or get help from the instructor if something is not clear. When writing a discussion, be sure to review the points listed above as to what you should be including in your discussion.

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