AC graphs can be dull as ditchwater if you're not careful so this is what I do:- Get the students to be DC electrons walking round room. Then get them to change direction every time I say 'Change.' Then tell them this isnt that accurate and give them 3 speeds, -3 to +3. Then go through these and to make it most accurate, linger on the -3 and +3 for the longest. Then get a kid to run up and down a number line to show how AC values change with time.
Modelling current flow in a series circuit: get whole group to sit in a big loop. Everyone sits on one hand - pass round some cell holders/cells/balls. Once everyone bar one has one state that you want to pass a different cell/ball/whatever around the circuit - this makes it easy to spot. To pass the new ball anti-clockwise the gap will need to move clockwise.
teacher demo of lighting a Bunsen with the spark from your finger after you've charge d yourself up on a Van Der Graff. If you've never tried it it's rather fun (doesn't work 100% of the time for me - depends on the charge you can get)
have always been a big fan of the van de graaff generator, but was introduced to a cool demo this year - aluminium cake cases piled on the top fly everywhere when switched on! Cutout paper tissue 'ghost' shapes also work well for this.
For teaching electrical conduction I use a singing gonk type thing - forgotten the name of them (anyone remember?), but they have a electrode on each hand and when you touch both hands it sings 'girl you really got me.' Best thing is if you get all of the class in a ring touching each other hands - noses you name it - If the circuit is complete it will sing round a loop of 25 kids. having a break in the chain with two students holding various conductors insulators will make it sing / not sing. They love it!