Reading a marked position on a number line

Your child uses labelled values and equal intervals to read a marked position on a number line. This gives the MOE P4 outcome on decimal representations a practical use: the distance between marks represents an increase in value. Reading the scale comes before deciding what the unlabelled point means.

• Identify two known values and the number of equal spaces between them, recognising that spaces and boundary marks have different counts.
• Find what one interval represents from the change between the labelled values, then use that same increase for neighbouring marks.
• Count forwards or backwards from a labelled point to locate the requested value, keeping tenths and hundredths in their correct places.
• Connect a decimal's position with its size: on a number line that increases to the right, a point farther right has a greater value.
• Keep the unit attached when reading a measuring scale, and check its labelled intervals before assuming each small space represents one unit.

When 0.4 and 0.8 are separated by four equal intervals, each interval represents 0.1, so the second interval after 0.4 reaches 0.6. Your child can count the remaining two intervals to confirm that the same step reaches the labelled endpoint, 0.8.

Basic questions include decimal readings, a mixed-number reading and a weighing scale with unlabelled smaller intervals. The Intermediate questions ask your child to read beyond the last labelled value, find an interval from a wider span, or calculate the difference between two marked positions. Challenge questions use a middle label to establish the interval or ask for a mass reading in grams when the scale labels are in kilograms. Before counting to the requested point, ask your child to explain how much one gap represents. After finding the value, check whether the answer must be a decimal, a mixed number or a measurement in a different unit.

Should my child count the marks or the spaces on a number line? Count the spaces between the two labelled marks when finding an interval's value. Five marks bound four spaces. Starting at the first mark as zero steps helps your child keep track of how many equal changes are needed to reach the last mark.

Does every small interval stand for one tenth? No. The labels determine the scale, so an interval might represent a whole number, a tenth or another amount. Your child needs to read two known values and the gaps between them before counting towards the point in question. The appearance of the line alone cannot supply the interval.

How does this page connect with comparing decimals? A number line makes the order of decimals visible through their positions. After finding a point's value, ask your child which labelled numbers lie on either side of it. That links reading the representation with comparing the values, while the separate comparison page develops place-by-place reasoning.