The development of a quantitative concept of rational numbers was explored in interviews with 16 fourth and fifth graders in two cities. High performers used a flexible and spontaneous application of concepts of rational number order and fraction equivalence, and a reference point, while low achievers tended not to. (MNS)

Exercises are used when beginning work with calculators to help pupils think about what they are doing. Four worksheets are included, with discussion of their objectives. (MNS)

Two computer programs are given to provide simulations, for any value of n, to keep count of the frequency of the first significant digit. (MNS)

Various types of computerized sorting techniques are demonstrated with cardboard materials children can manipulate. Bubble, ripple, and binary sorting are each illustrated. (MNS)

An example is given of how to help students who have obtained a correct answer by a wrong method. They are asked to suppose that a child has found an easy method for division, and eventually write a computer program to show the correct method. (MNS)

Stresses that powers are all based on geometric progressions which start at unity. Various patterns are discussed. (MNS)

Involving students in generating and solving their own problems is proposed. A method for generating problems by using a number puzzle is presented. Ideas for using the "what if not" technique are also given. (MNS)

Activities involving estimation of the number of objects in a configuration can motivate students to consider parametric models. (SD)

The place of binary arithmetic in the curriculum is discussed, then uses of binary coding for methods of automatic error correction in computers and calculators are analyzed. (DT)

Determining the day of the week on which Christmas falls each year is explained. (DT)

A method is explained for using the calculator to determine the day of the week on which any given date falls. (DT)

A sequence of activities leading to the concept of Pi is suggested. (DT)

This article discusses the use of the balance beam in developing concepts of equality and inequality and in showing the basic arithmetic operations. (DT)

A card game is described which gives students practice with adding integers and which also develops the concept of "opposite." (DT)

The rationale for teaching different number bases is discussed, and an approach for teaching the base 4 system is suggested. (DT)