Earth Warp/Cleaning the beach

At the start of this challenge, the text "The children quickly find Ollie hiding on the beach." shall appear on the screen; once you have pressed Space the text of "Ollie is examining something which is strapped to his wrist. It looks like a very large watch." shall appear beneath it. Once you have pressed Space for the second time, the text of "'I think the probe is near the beach' says Ollie, 'but there is so much pollution here that my wrist computer just cannot find it!'" will appear beneath that - and once you have pushed Space for a third time, the text "Ollie thinks that if the children help him clear up the beach, he will be able to find the probe. Do you want an easy or a hard game?" shall appear on the screen, with two options "Easy" and "Hard" and the text "Press SPACE to select and RETURN to choose." below it (the difficulty you select for the challenge determines what is on the beach's X-axis).

If you select "Easy", an overhead grid view of the beach with the letters A through H on its X-axis and the numbers 0 through 7 on its Y-axis, along with nine objects (seven of which are rubbish, but two of which are not) in randomly-generated positions, shall appear on the screen with the text "You must type a letter and a number to find the rubbish on the beach." below it; after you've pushed Space for a fourth time, the text "For example: (X,X)" (X,X being a randomly-generated blank position on the beach) shall appear on the screen as a crosshair locks onto it and flashes five times, followed by the text "Oh dear! There is nothing there!". Once you have pressed Space for a fifth time, the text "Now you try." shall appear on the screen, followed by "Type a letter" with a left bracket and a cursor flashing above it - and after you've typed a letter between A and H, a comma shall appear after the letter you typed, as the text "Type a number" appears below it. Once you have typed a number between 0 and 7, a right bracket will appear after the number you typed, as the crosshair locks onto the position you have entered and flashes five times; if there is nothing in that position, the text "There is nothing here." shall appear on the screen, but if there is a piece of rubbish in that position, the text "You have found a/an bottle/crisp packet/dangerous can/old shoe/paper cup/sweet wrapper/tin can." will appear, and if there is a sea creature there the text "A crab/star fish! That is not rubbish!" will appear. In all three cases, you will then have to press Space to continue (in the case of there being a piece of rubbish in the position you entered, it will be moved into one of the seven boxes on the right side of the screen) - and once all seven pieces of rubbish have been moved into the boxes on the right side of the screen, Ollie's probe shall surface, and the text "You have cleared up all the rubbish and Ollie is delighted!" will appear on the screen. Once you've pushed Space for a minimum thirteenth time, the text "Now it is easy for Ollie to find the probe!" shall appear on the screen; once you have pressed Space for a minimum fourteenth time, the game will proceed to its fourth challenge, in which you must continue a pattern of colours to cross a river.