i also made an inventions lesson. i did it with a 3rd grade middle school class, but it can be adapted for older - high school students should be able to talk more in English during the inventions game.
first introduce inventors - ask class what an inventor is (it is written in Korean, so i get them to explain in English).
then they have a worksheet and have to match the inventor to the invention. I laminated 10 colour copies of the worksheet without the sentences on the back so the students can see the pictures in colour. The i copied in black and white a worksheet for each student with with sentences on the back so as you go through the answers they can fill in the correct words.
Go through the answers with them. surprisingly they didn't know Facebook - i kind of thought everyone did - so instead i explained it is similar to Twitter and MySpace and MSN Messenger on the internet, a way to chat to friends.
After the first answer, i went through the sentence structure with them and got them to make a sentence each time we went through a new invention.
Then you do the game. This may be a little complicated. the students have word cards and picture cards. the aim is to find picture cards from their friends to match their words. they have to keep the word card and get new picture cards. they should be trying to use the vocabulary on the cards by reading carefully. encourage the to ask for help!
there are 30 pictures and 30 word cards. i did this with a class of 15 and a class of 32. i have made 3 sets of cards. so for the bigger class they had 3 pictures and 3 word cards. for the smaller class they had 6 pictures and 6 word cards. depending on the levels, you will need to decide how many they can cope with!
at the end, if there is time i go through some of the inventions with them... i point at a square on the screen and ask if they know this in English (sometimes they do, sometimes they don't). i write the English name on the board and get the students to show me who has the card.
for really high level students, you could ask them to write some sentences about what each object is for - this requires homework maybe! and honesty on their part - they need to think of new sentences rather than what has been written on the word card!
i laminated the card game so it can be reused and printed it in colour - after only 2 lessons some have gone missing already so i will need to make some more!