Study guide: Read Small Data Tables Carefully

Ideas to explain in your own words

• A table organizes information into rows and columns. A row can represent one item; a column label tells what its values mean. The same number can mean a count, a length or a code. Read both labels before interpreting a cell.
• Data can use numbers to count or measure, and digits can also be labels. A classroom item code 007 identifies an item; adding item codes does not produce a meaningful total. In this model Count is a quantity and Code is a label. The column meaning controls what operations make sense.
• A blank or unknown field does not mean zero. Zero is a recorded quantity; missing means the value was not supplied. Treating missing values as zero changes conclusions. A clear record uses a consistent missing marker and explains it in the key.
• A categorical table records choices as labels. Counting each label produces a summary. The summary should account for every record and should not include missing choices in a known category. In this exercise each supplied row is one fictional choice, not a real learner’s identity.

Useful vocabulary

row

One item or record in a table.

column

A labeled field repeated across rows.

missing

A value not supplied or known.

Watch your reasoning

• Do not read a nearby cell from a different row or column.
• Digits in a code do not make it a quantity.
• Never fill an unknown answer with zero just to make a table look complete.
• Do not count the category heading as an additional record.

Make a practice plan

1. Draw or tell one computing idea from each of the four lessons. Give one example of using each idea.
2. Use the example to explain one mistake to avoid.
3. Try the unit review before opening the explanations.
4. Try the new task on paper or say your answer. Then compare your steps with the example answer.