Work in pairs, move screen so partners cannot see each other's screens.
In Excel enter a number in the range 1-999 in cells A2-A27 (26 in all). The numbers should not be in order. Choose a number to be your 'battleship', tell your partner the number but not the location. Take alternate 'shots' to locate and sink the partner's battleship - call 'B2', 'F2', etc. Record the number of shots taken by your partner.
Work out the class average for the number of shots required to locate the battleships. What are the minimum and maximum shots required to locate a battleship?
Now sort the numbers into ascending order (select them and choose Data/Sort). Choose a number as the battleship and then take turns to locate it as before. It should take fewer shots to locate the battleship this time - why?
Work out the class average of the number of shots taken. What are the minimum and maximum shots required to locate a battleship?
In this game you place numbers in a row in the spreadsheet according to a formula. The row number is calculated by adding up the digits in the number and taking the last number of the sum. For example, ship 456 has sum 15 so appears in row 5. Now when the partner has the number of the ship to find he can work out which row it is in and find it very quickly.
Extension:
Work out your own way of encoding the row number but don't tell your partner. Now he will have to try to work out your code from the information you supply after each shot.
Search a list of the members of a class. Count number of items searched for each search.
Use the method developed earlier for finding mystery numbers to search a list.