These activities require you to either project your computer screen onto a television or to gather your whole class around the computer.
http://www.bbc.co.uk/education/wordsandpictures/longvow/poems/fpoem.shtml
As a whole class you can read or listen to a poem, and then complete the Sound Search and Find the Word activities. (Note: requires Shockwave)
http://www.kidscarnival.com/PenguinSub.html
Choose one of the math games listed in the Ticket Window. Each student in the class can participate by displaying their answers with the correct number of fingers or a number card. You may want to choose one student to be The Official Mouse Controller, and he/she will click on the answer that a majority of the class thinks is correct.
http://www.funbrain.com/cgi-bin/cr.cgi?A1=s&A14=easy
The object of this game is to get as much money in the piggy bank as possible. To earn money you must be able to make change. For example, if The Amount of the Sale is $0.29 and The Amount Paid is $0.50, the whole class needs to decide what change must be given. You may want to pass out play money or another math manipulative.
http://www.kidspsych.org/
After the long welcome sequence choose the "for ages 6-9" or the "for ages 1 to 5" link. You will then be given a choice of activities. Some of the games, such as I Spy, are good whole class activities.