How many cats are on the farm?

3/5/2010

Today we had an interesting problem to solve and kids had a lot of fun.

I divided math group into two subgroups and asked each subgroup to solve the problem independently.

Here is the problem.
There are cats and chickens on the farm. A cat has 5 claws on one leg and a chicken has 4 claws on one leg. There are 104 claws all together. How many cats are on the farm?

One group gave me an answer right away: 5 cats and 1 chicken with only one leg :)
Because the answer was wrong kids continued solving it.
In a little while one group gave me the correct answer: 4 cats, but when I asked them how many chickens they told me 24. I guess all those 24 chickens had 1 leg and 1 claw :) Kids understood what they did wrong and gave me the correct answer: 3 chickens. The second group solved that problem just after the first one.

Then I told children that there is another solution. After a while both groups gave me the correct answer: 2 cats and 8 chicken.

After that I told them that this problem can have another answer. They could not solve it for a while and then I gave them a hint that number of cats can be any including 0,1,7, etc. They tried 0 and it worked. 0 cats and 13 chicken.