Playing intervals and chords from the C position
playing intervals
Of course, you've already been playing intervals in every music snippet so far. There's an interval between every successive note by definition. However, you probably haven't paid any attention to the actual interval counts. Learning to recognize certain interval counts is a valuable skill in learning to play intervals sequentially as well as in chords.
If the keyboard keys were all the same width and lined up without recessing the black keys, it would be pretty easy to learn to recognize and play a given interval because that physical distance would always be the same everywhere on the keyboard. Of course, playing on this keyboard would be even more of a challenge for those with small hands. But with the keyboard we have, it's necessary to pay attention to the fact that there are two rows of keys and that both must be included in counting intervals. Secondly, those pesky gaps in the row of black keys means that the "pattern" for a given interval looks different depending on whether you cross one of the gaps.