Exam practice

Data means facts recorded as they are, before anyone has made sense of them. Information is data that has been organized and processed so that it means something and answers a question.
Example: the marks of every student in a class test are data. “The class average went up from 54 to 61, and 5 students got over 80” is information, found by working out averages and counting.
(Or: a shop’s bills for a month are data; “sugar sells most in the week before Dashain” is information.)

1. The choices overlap: someone who lives exactly 1 km or 3 km away fits two choices.
2. They don’t fit everyone: someone who lives more than 5 km away has no choice to tick.

Better: ☐ less than 1 km ☐ 1 km to less than 3 km ☐ 3 km to less than 5 km ☐ 5 km or more. (Or ask for the number: “About how many kilometers do you live from school?”)

It has 5 records (one row per friend) and 3 fields (name, age, favorite sport). The header row holds the fields’ names: Name, Age, Favorite sport.

• i.=SUM(B2:B8)
• ii.=AVERAGE(B2:B8)
• iii.=MAX(B2:B8)

If Tuesday’s number is corrected, all three formulas work themselves out again at once, and the new answers appear. Nothing has to be worked out by hand.

Each row is one student’s record. If only the Marks column were sorted, the marks would sit beside the wrong names (Asha would seem to have 91), and the table would be wrong. Sorting moves whole rows, so each mark stays with its student.

• i.Mango 10 ÷ 20 = 50%; apple 5 ÷ 20 = 25%; banana 4 ÷ 20 = 20%; guava 1 ÷ 20 = 5%. Together: 100%.
• ii.Title: “Favorite fruit of 20 students”. The fruits along the bottom axis, named “Fruit”; the number of students up the side, named “Students”, starting at 0 and going up in 2s to 10. Bars of 10, 5, 4 and 1.
• iii.Yes. Every student picked one fruit, so the answers are parts of one whole (the 20 students) and add up to 100%. A pie would show that mango is half of all the answers. With only four fruits, the slices are easy to tell apart.

The axis starts at 40, not 0, so the bars show only 10 and 5: the shop’s bar looks twice as tall, though 50 is only 5 plates (about one ninth) more than 45.
Redrawn honestly: start the axis at 0 and number it (0, 10, 20, 30, 40, 50), name both axes (“Shop”, “Plates sold in a day”), and give it a plain title such as “Plates of momo sold in a day”. The two bars then look almost the same height, as they should.

Any three, such as:

• what it is about, or where and when the data is from (no title);
• what the bars stand for, and in what units (no axis names: students? rupees? kilograms?);
• how big the numbers really are, or how big the differences are (no numbers on the axis);
• whether the axis starts at 0, so whether the heights can be compared at all.

Any three, such as:

• Formulas do the adding, averages and counting, without mistakes.
• When a number changes, every answer and chart that uses it changes by itself.
• It can sort the records in a moment, by any field.
• It draws charts from the table in a few taps.
• The file can be copied, shared with the teacher and kept safely.

A model plan:

• Question: “On a school day, about how many hours do you spend looking at a phone, TV or computer screen, not counting class? ☐ less than 1 hour ☐ 1 hour to less than 2 hours ☐ 2 hours to less than 3 hours ☐ 3 hours or more”. The choices don’t overlap and fit everyone.
• Fair and private: ask everyone the same question in the same words, without telling them what answer is “good”; don’t ask names, so people answer honestly; share only the counts.
• Recording: count the answers with tally marks, then put them in a spreadsheet, one row per choice, and add up the total with =SUM.
• Chart: a bar chart to compare the groups (which is most common), with a title, named axes and an axis starting at 0. A pie chart would also work for “what share of students spend 3 hours or more”, because each student is in exactly one group.