Mathematics
Advanced
50 mins
Teacher/Student led
Learning Goals
Learning Outcomes
Lesson Files
+80 XP
What you need:
IWB/Projector/Large Screen

Probability as a Decimal and Percentage

Learn to write probabilities as fractions, decimals and percentages, then use these forms to compare chances on fair spinners and games of chance.

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    1 - Getting Started ~4 mins

    Illustration for Getting StartedPicture a spinner split into ten equal segments, like a prize wheel at a school fair. Each spin is just as likely to stop on any one of them.

    Key point

    If we say the chance of landing on one segment is 1/10, what would that same chance look like written as a decimal? And as a percentage?

    👇 Mark your steps as done as you complete them.

    +5 XP

    2 - Watch and Notice ~8 mins

    The interactive shows four fair spinners in turn — a ten-segment wheel, a four-segment wheel, an eight-segment wheel, and a fair coin. For each one we read the chance of a single segment three ways: as a fraction, a decimal, and a percentage. Watch how we get from one form to the next, and try reading the next form before it appears.

    👇 Mark your steps as done as you complete them.

    +10 XP

    3 - Write It Three Ways in Your Copy ~3 mins

    COPYBOOK MOMENT

    In your maths copy, write each of these probabilities three ways in a row: the fraction first, then the decimal, then the percentage. Keep one set under the other so they line up.

    • 1/10
    • 1/4
    • 1/8
    • 1/2

    Then circle the form you find easiest to compare with.

    +10 XP

    4 - Try It Together ~10 mins

    Today we work this ten-segment wheel together — think of it as a school-fair prize wheel where some spaces win and some don't.

    Key point

    A prime number has exactly two factors: 1 and itself. On this wheel, 2, 3, 5 and 7 are the primes (each divides only by 1 and itself), so four of the ten spaces are winners. That makes the chance of landing on a prime 4/10.

    Before we spin, say the chance of a prime three ways: 4/10, then the decimal, then the percentage. Then we record whether each spin is a hit (a prime) or a miss, and see how the run compares to our 4/10 prediction.

    +15 XP

    5 - Class Challenge ~8 mins

    Key point

    Now we convert probabilities on the battery slider. Think of the battery as a percentage bar: an empty battery is 0% and a full battery is 100%, so wherever the slider sits IS the percentage we are converting to. To show 1/10, for example, we fill the battery to one tenth of full, which is 10%.

    Each round gives a fraction. Set the battery slider to the matching percentage. We'll work these in order: 1/10, then 1/4, then 3/8, then 3/5, the one we just worked out as 0.6 = 60%, and finally 7/10.

    Convert the probability

    +15 XP
    Pupil practice
    Module 7 · Data, Chance and the Co-ordinate Plane Data & Chance
    Lesson 102 · Probability as a Decimal and Percentage
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