Practicum-Sharing a Lesson

During my practicum I was able to stand in for my mentor teacher to teach a lesson in rounding for his 5th grade students. The objective of the lesson was for the students to recognize the place value that we were asking them to round, and then to correctly round up or down depending on the value of the number to the right of the place value they were to round to.  The students reacted very well to using two distinct tools to help them round, the first step was to underline the number that was to stay the same or to be rounded up, and then to put an arrow over the top of the number that determined whether to round up or not. The only real issue that came up was that students repeatedly stated that the number in the first place to the right of the decimal was the "oneths place", I then wrote on the board and asked them to take a note in their composition notebooks that the one "trick" to remember with place values after the decimals is that there are no "oneths" and the place value to the right of the decimal starts with tenths and goes up from there just like it does to the right of the decimal place.
      Throughout the lesson I was able to walk around the room to check for understanding by looking at their notebooks to check on the correctness of their rounding of the example problems on the board. Also, during the warm up section I was able to have students get into groups and have a representative come up and answer their assigned problems and then have their peers agree or disagree with their answers.
      Overall I feel like the class went very well, if I had a chance to teach it again I would introduce the "trick" about place values at the very beginning because that was supposed to be a prerequisite skill for the lesson that obviously was not something that all of the students were aware of.