I have a book called Cross Over. The publisher is Lauren Robbins. The level is third grade. I chose the unit 2. The topic is "Do an experiment" Main language is verbs for an experiment, vocabulary of material and equipment, infinitives and gerunds, clauses or first conditional and simple present. Communicative aims are debates and explanations about the experiments and danger inside a lab. OK. I think the book has the tasks graded even it starts with a brief introduction difficult for the learners but it goes to the easy to difficult introducing the vocabulary of the material, verbs and words to carry a sequence and the measuring of the substances, with small pictures showing the steps to follow then gives anothers examples where the learners have to complete and describe the material and process of the experiment.
Therefore it concludes that if it meets the aim required although in the case of some topics for example the clauses (first conditional) it only gives a simple explanation and it handles it in a general way it doesn't start from the easy to difficult. Here I can say the publisher has had into account the challenge for the learners are faster and I consider that for those that need further practice if there would be a little more even the book has exercises of feedback at the end of the unit and from all of the book.
I also observe with regard to activities of listening they aren't graded it would need to start with the easy measuring the speed of conversation because they don't pick up for the new words and besides the book doesn't have the tape scripts and it would be fine that includes the vocabulary of the materials and equipment first. The book possesses several activities in a book called teacher's guide which gives a a wide variety of ideas from games to the most complex topic such as debates, contests, brainstorming sessions, etc, although some of them don't work in class but we can support in them. In case of a mixed ability classes it proceed with an exam to identify the different types of the students and establish the small groups that it be formed to work with the different types of student. They work and help among them.
As to slower learners I get down my level of english and try to start from zero in case they don't undertand I begin with a simple vocabulary and they have to do it in several ways. this could be a bingo, memorama, games board, etc. to practice it and learn quickly or make a cards and they use them to do sentences and go along, graded the work so on until I level them and fot them are faster I put more complex tasks, such as make up conversations, write and expose topics and explain them to their partners.