Android keyboard behaviour changed after updated to Jelly Bean
This new feature is called Next word prediction. You can easily disable it to restore the ICS behavior but it's a bit hidden:


Go to Settings > Language &amp; input
Tap on the setting icon beside Android keyboard under the Keyboard &amp; input methods section
At the bottom you'll find Advanced settings, tap it
There you'll find Next word prediction, uncheck it:




After that, typing I followed by space will bring up the punctuation again instead of predicted words.