Keep a constant level of light in your room even as natural light changes.
Similar to auto brightness on a smartphone or tablet, have sensor based input adjust the level of room lighting based on the sensed level of light.
Have fun while learning and getting to know more about your language skills.
An app that gives you a sentence to rewrite. It then analyzes your sentence and gives you a score based on how developed your vocabulary is. It will also show you other possibilities for rewriting the sentence.