Remove the tank cover and check the water level after the fill valve has shut off. It should be about one inch below the opening of the overflow tube. If it is significantly lower than that, there may not be enough water in the tank to fill the bowl after a flush. Correct this by adjusting the float.
The average child can do this during the second half of this year. Between 24-36 months, children are typically able to work simple insert puzzles (e.g., completes a three-piece simple puzzle where pieces are whole objects). Also, children can remove a part from a toy (e.g., a wheel) and replace it.
1 Most babies say a few simple words such as 'mama' and 'dada' by the end of 12 months - and now know what they're saying. They respond to - or at least understand, if not obey - your short, one-step requests such as, 'Please put that down.'.  Baby talk at 18 months. By this age, babies may use up to 20 simple words, like daddy, dog or cup. They should also be able to point to people, objects and body parts you name for them. They repeat words or sounds they hear you say such as the last word in a sentence.