Start with this short video, then scroll down for the full guide.
Why This Matters for Nursing: Accurate measurement is essential for dosing medications, recording vital signs, and interpreting lab results. Lab safety principles apply to clinical settings where you handle hazardous materials and body fluids.
Scientific measurement requires precision, accuracy, and proper units. Lab safety protects you and patients from hazards.
Metric Prefixes (big to small): "King Henry Died By Drinking Chocolate Milk" Kilo β Hecto β Deka β Base β Deci β Centi β Milli
Significant Figures: - All non-zero digits are significant - Zeros between non-zero digits are significant - Leading zeros are NOT significant
| Measurement | Base Unit | Symbol |
|---|---|---|
| Length | Meter | m |
| Mass | Gram | g |
| Volume | Liter | L |
| Temperature | Celsius | Β°C |
| Prefix | Symbol | Meaning |
|---|---|---|
| Kilo- | k | 1,000 |
| Centi- | c | 0.01 (1/100) |
| Milli- | m | 0.001 (1/1,000) |
| Micro- | ΞΌ or mcg | 0.000001 (1/1,000,000) |
| Term | Meaning | Example |
|---|---|---|
| Accuracy | How close to the TRUE value | Hitting the bullseye |
| Precision | How close repeated measurements are to EACH OTHER | Hitting the same spot repeatedly |
Ideal: Both accurate AND precise
Rules: 1. Non-zero digits are ALWAYS significant: 123 has 3 sig figs 2. Zeros between non-zeros ARE significant: 101 has 3 sig figs 3. Leading zeros are NOT significant: 0.01 has 1 sig fig 4. Trailing zeros after decimal ARE significant: 1.00 has 3 sig figs
| Number | Sig Figs |
|---|---|
| 250 | 2 |
| 250. | 3 |
| 0.025 | 2 |
| 2.50 | 3 |
| 1000 | 1 |
| 1000. | 4 |
| Equipment | Purpose |
|---|---|
| Safety goggles | Protect eyes from chemicals/splashes |
| Lab coat/gown | Protect skin and clothing |
| Gloves | Protect hands from chemicals/pathogens |
| Fume hood | Ventilation for toxic fumes |
| Fire extinguisher | Put out small fires |
| Eye wash station | Flush chemicals from eyes |
| Safety shower | Wash chemicals off body |
| Symbol | Hazard Type |
|---|---|
| Flame | Flammable |
| Skull | Toxic/Poison |
| Exclamation mark | Irritant |
| Corrosion | Corrosive |
| Health hazard | Health risk |
| Biohazard | Biological hazard |
Used to express very large or small numbers:
Format: a Γ 10βΏ (where 1 β€ a < 10)
| Number | Scientific Notation |
|---|---|
| 5,000 | 5 Γ 10Β³ |
| 0.005 | 5 Γ 10β»Β³ |
| 602,000,000,000,000,000,000,000 | 6.02 Γ 10Β²Β³ |
Question: How many significant figures in 0.0250?
Step 1 β Know the significant figures rules. Significant figures (sig figs) tell you how precisely a number is measured. The rules: 1. All non-zero digits (1-9) are ALWAYS significant. 2. Zeros BETWEEN non-zero digits are significant (e.g., 101 β the middle 0 is significant). 3. LEADING zeros (zeros before any non-zero digit) are NOT significant β they're just placeholders. 4. TRAILING zeros AFTER a decimal point ARE significant β they show precision.
Step 2 β Apply to 0.0250. Identify each digit: - "0." β leading zero. Not significant. - "0" (second zero) β also a leading zero. Not significant. - "2" β non-zero digit. Significant. β - "5" β non-zero digit. Significant. β - "0" β trailing zero AFTER a decimal point. This tells us the measurement was precise enough to know this digit is zero. Significant. β
Step 3 β Count. Three significant digits: 2, 5, and the trailing 0.
Answer: 3 significant figures (the 2, the 5, and the trailing 0 after the decimal).
Why does this matter? In nursing, precision matters. If a drug concentration is 0.0250 mg/mL, the trailing zero is there for a reason β it tells you the concentration was measured precisely to 4 decimal places, not rounded. Dropping significant figures can mean dosing errors.
The worked examples and practice problems are the part that actually prepares you for the TEAS.
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