A good results table has one column for the independent variable and columns for each repeat of the measured variable. Add a column for the mean where repeats exist. Write the unit once in each heading.
Tables appear in every practical-style question, and they are the step that makes anomalies and patterns visible. This lesson follows selecting variables in practical-data interpretation.
How do you build the table, step by step?
- Decide the columns from the variables. Independent variable first, then the measured readings, then any calculated values such as a mean.
- Write the quantity and unit in each heading. For example Temperature / °C and Time / s.
- Put only numbers in the cells. No units, no words, unless the reading is an observation.
- Keep the same number of decimal places down a column. Match the instrument you used or were told about.
- Order the rows by the independent variable, smallest to largest.
- Add a mean column when the experiment was repeated, and show the working for one row nearby if space allows.
Worked example
Invented data. A class measures the time a tablet takes to dissolve in water at five temperatures. Each temperature was tested twice.
Raw readings are listed first.
20 °C gave 84 s and 88 s, and 30 °C gave 52 s and 50 s. 40 °C gave 33 s and 35 s, 50 °C gave 21 s and 23 s, and 60 °C gave 14 s and 14 s.
| Temperature / °C | Time 1 / s | Time 2 / s | Mean time / s |
|---|---|---|---|
| 20 | 84 | 88 | 86 |
| 30 | 52 | 50 | 51 |
| 40 | 33 | 35 | 34 |
| 50 | 21 | 23 | 22 |
| 60 | 14 | 14 | 14 |
The means come from adding each pair and halving:
- 20 °C: (84 + 88) ÷ 2 = 172 ÷ 2 = 86
- 30 °C: (52 + 50) ÷ 2 = 102 ÷ 2 = 51
- 40 °C: (33 + 35) ÷ 2 = 68 ÷ 2 = 34
- 50 °C: (21 + 23) ÷ 2 = 44 ÷ 2 = 22
- 60 °C: (14 + 14) ÷ 2 = 28 ÷ 2 = 14
The independent variable is on the left, units appear once per heading, and the rows run from coolest to hottest.
What mistake is easy to make?
Mistaken table: headings “Temp” and “Time”, with cells reading “20°C”, “84 seconds”, “30 °C”, ”52s”.
The units are repeated in different forms, the headings name no unit, and the cells mix styles.
Two problems matter here. A heading without a unit leaves the reader guessing, and units inside cells make the column impossible to scan or plot.
The correction is to write the headings as Temperature / °C and Time / s, then enter 20, 84, 30, 52 and so on as plain numbers.
Check yourself
1. A table heading says “Volume of gas (cm³)” and every cell says “12 cm³”, “24 cm³” and so on. Rewrite the heading and the first two cells.
Show answer
Heading: Volume of gas / cm³ (or Volume of gas (cm³) if that is the form your school uses, but then keep it everywhere). Cells: 12 and 24, with no units.
2. Three repeat readings of a time are 12.4 s, 12.6 s and 12.5 s. Work out the mean.
Show answer
(12.4 + 12.6 + 12.5) ÷ 3 = 37.5 ÷ 3 = 12.5 s.
3. A student plans a table with “Time / s” in the first column and “Concentration / mol/dm³” in the second, but the investigator changed the concentration. What should change?
Show answer
The independent variable, concentration / mol/dm³, should go in the first column, with the measured time / s to its right.
Where does this lead next?
A tidy table is what lets you see a reading that does not fit, which is the skill in identifying an anomalous reading. If the experiment involved a gas, you may also want to read the apparatus diagram first. The mixed practice set brings the skills together.
Layout errors are easy to repeat without noticing. A teacher in online one-to-one Chemistry tuition can read your tables and catch them early.