Lots of teachers have written in saying how they use the Genki English card game cards to teach comparatives, and more importantly, how much the kids enjoy
The basic idea is that you print out a set of cards for each group and
the kids have to use them to make sentences
e.g. The duck is faster than the tortoise
The giraffe is taller than the butterfly
The rhino is heavier than the bird.
The reindeer is younger than the dragon.
You can also make a game out of it by choosing one category e.g. "top
speed" and the teams have to race to see who can make a sentence first,
using the cards they have. But once they've used a card they can't use
it in subsequent rounds!
Or you can give each kid two cards and see who is quickest to make a correct
sentence from the data on the cards.
To be honest I much prefer to use the cards in their original way, to get the kids fluent at numbers, but if it helps make a usually boring
grammar point a little more exciting, it's probably worthwhile trying out!
There are 18 cards that anyone can download above, and another 16 to download
if you are a CD Owners' Club member. Or you can now buy the cards in pre-printed packs ( and 2 packs are also included in the Superpack).