Basic concepts - this is such a broad category! Preschool programs do a lot of work on teaching basic concepts like numbers, letters, colors and shapes but the term 'basic concept' is used to refer to so many more vocabulary groups. Toddlers and preschoolers have a lot of work to do to learn the words that describe positions, size, quantity, texture, comparisions, time or sequence and emotions. These words are critical to understanding directions (eg. 'You can take the big cookie') and make it so much easier for your child to communicate clearly with you (eg. 'Mom I want to wear the yellow shirt').
Learning basic concepts seems to happen almost effortlessly for many children and it's so interesting to watch the progression. Earlier this week, I was driving my 2-year-old daughter to her dayhome and she asked "Mom are you behind me?". The concept of 'behind' was emerging...she knew the word and knew that it referred to a position, but she didn't yet know what position. I explained that I was in front of her and that the stroller was behind her (in the back of our vehicle). Just this morning, while we were taking the same drive, she stated "Mom, you're behind me" - just like that the concept was mastered. Several months ago, my husband and I were showing our daughter different sizes of balls and asking her which one was big and which one was little. She wasn't yet very consistent at understanding these words, but just last night while I was putting her to bed, she told me that she was a 'little honey' and I was a 'big honey.' Yet another concept is mastered.
Pay attention to the types of words your toddler is using and how well they're able to follow directions you give them. You may have some great examples of your own about basic concept learning, or you may find a few that your child needs help learning. You can seize the 'teachable moments' like in my first example or find fun ways to teach these concepts clearly to your child like my second example shows.