This is the PowerPoint file I use to teach decimals all at once for my 5th grade classroom in whole group instruction on dry-erase boards (lots of drill and practice; as students finish adding/subtracting decimal problems, they can always write their answers in standard form as a fraction, in word form, and expanded form). I use place value blocks when I do and give students a conceptual/visual to understand when I do.
This file has animation and sound with each question. For example, start the slide show and click. The first problem appears. Have students work it out, click again for the answer, click again for the next problem, etc. The "fast" students can always show their work on the board as they finish by writing their answers in the other forms. That will give time for the "slower" students to work and get help from the teacher as needed.