Play Your Cards Right!
Background
Probability is introduced in the Numeracy Strategy at the top of Key Stage 2. At this level, children need to start to discuss and explore how likely events are to happen, using appropriate vocabulary. They will start to compare events and say which of two outcomes is more likely to happen. For example, children need to know that it is more likely to rain in August than it is to snow. This will lead to events being placed on a scale of likelihood, starting with ‘no chance’ and ending with ‘certain’.
Another important aspect of probability is considering probabilities of events with equally likely outcomes, such as rolling a fair die, where probabilities can be accurately placed on a probability scale. Children need to start to recognise when an outcome has an even chance, for example rolling an odd number on a normal die.
‘Play Your Cards Right’ uses the familiar context of card games to develop these concepts.
Teaching suggestions
Spydrax has a set of cards numbered 1 to 9. In the first level of the game, Spydrax turns over one card and asks the children to guess whether the next card will be higher or lower. If correct, the player wins a chip. It is important to move children on from pure guesswork towards using probability to help them make informed choices. If possible, you may wish to introduce the activity to the whole class, and to play the activity together initially, agreeing on a whole-class decision.
Children will benefit from playing this activity in pairs or small groups, rather than individually, to give them the opportunity to discuss and explain their thinking, before ‘making their bet.’ Encourage children to see how few turns they can take to win their six chips.
Key teaching/learning points include:
- When a card is chosen from a pack at random, all cards have an equally likely chance of being picked.
- To work out whether the second card is more likely to be higher or lower, children need to work out how many of the remaining cards are higher/lower than the given card.
- When a three is shown, although it is more likely that the next card will be higher than lower, it is perfectly possible that a lower card will come next.
Assessment questions:
- If the first card is a seven, is the next card more likely to be higher or lower? How did you know?
- Are there any first cards where you can be sure that your ‘bet’ will be correct?
- Which is the most awkward card to be dealt? Why?
In the second level, Spydrax places all 9 cards in a line. As he turns each one over, children have to ‘bet’ on whether the next card will be higher or lower. It may be helpful for children to have a set of 0 to 9 cards. They can then turn over the cards as they appear so that they can see how many cards are left that are higher and how many are lower. Again, it will encourage reasoning if children work in pairs and have to agree before they bet.
At the third level, when Spidrax deals a card from the pack, children have to choose the correct probability for the next card being higher. They have the choices; ‘no chance’, ‘poor’, ‘even’, ‘good’ and ‘certain’. Children need to recognise that, for example, if a seven is shown, there is a poor chance that the next card will be higher because there are only two cards higher than 7 whereas there are six cards lower than 7. A visual reinforcement of this reasoning is given after each correct answer. It would be helpful to give children a set of 1 to 9 cards to place in order in front of them to help.
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