Why laravel 5.1 form class not fund?

I am using laravel 5.1. I am working with form but browser is showing an error like this.

FatalErrorException in 44a7f556a7d1beef3d09ba2ba2e3c7f0 line 7:
Class 'form' not found.

I have already try to solve this problem by these command......

1) composer require illuminate/html
2) update in app file provide and aliases section

I don't know why happening this. Any type of help will be appreciated. Thanks

via Chebli Mohamed