Will it be 90 kids all at one time? I would end the powerpoint with a visual quiz on something like live vs. dead and animal vs. plant. If the budget allows a color worksheet would be cool for them to take home. Make sure you have the pnwmas logo on the page with the website. You could also if the class is small enough, after the pp to have them line up and go from one side to the other to answer questions. For example, if you think xenia is a plant move to the left, if you think it is an animal move to the right, if you don't know for sure stand in the middle. Kids that age like active participation but remember it will also get them really excited!!! Good luck. Hope this helps.