Before reading any column, look at the scale on the side. It may go up in 1s, 2s, 5s or 10s. Go across from the top of the column to the scale to read its value. If the top stops halfway between two gridlines, the value is halfway between their numbers. To compare, read both columns and subtract. A side-by-side column graph shows two groups for each category: use the key to tell the groups apart.
Explore this idea with maths tools
Maths you can move
Build 8 + 5
Tap two gold counters to fill the ten-frame.
8 in the frame + 5 waiting. The total stays the same.
Words to know
- scale
- the numbers up the side that show what each gridline is worth
- gridline
- a line across the graph at each step of the scale
- side-by-side column graph
- a graph with two columns for each category, one for each group
Worked examples
The scale goes up in 5s. A column reaches the 4th gridline. What is its value?
- 1.Each gridline is worth 5.
- 2.4 gridlines: 5, 10, 15, 20.
= 20
The scale goes up in 2s. A column stops halfway between 6 and 8. What is its value?
- 1.The top is halfway between the gridlines for 6 and 8.
- 2.Halfway between 6 and 8 is 7.
= 7
Chocolate: Saturday 40, Sunday 25. How many more were sold on Saturday?
- 1.Use the key to find each day's column: 40 and 25.
- 2.40 − 25 = 15.
= 15
For parents
Method: Read the scale first
What to say: What does the scale go up in? Where exactly does the top of the column land?
Common mistakes:
- Counts gridlines as ones and ignores the scale.
- Reads a column that stops halfway between gridlines as the gridline below.
- Reads a column that stops halfway between gridlines as the gridline above.
- Answers 'how many more' with the value of the taller column.
- Adds the two columns when asked for a difference.