The teaching of probability is currently being reinforced in many countries, as it is visible from new curricular documents such as the NCTM Standards (2000), where the acquisition of a precise language in connection to chance and probability is considered to be a main learning goal. On the other hand, textbooks are an important resource for teachers who can find in these books ideas and activities to facilitate students' learning. In recent Spanish curricular documents (M.E.C., 1992) the teaching of probability is introduced at earlier ages with a teaching methodology based on simulation and experimentation. A main concern is children's progressive acquisition of a precise language in connection to chance and probability. This curriculum is not an exception, since we find similar concerns in curricular documents from other countries, such as the United Kingdom or the United States. On the other hand, when children are first taught probability, they have frequently used terms and expressions to refer to randomness, sometimes with a meaning different to what is usual in the mathematics classroom. All these reasons suggest the interest to carry out an empirical study to determine the specific language that about chance and probability is presented in the textbooks.