This book highlights the effect of using scientific calculators in Mathematics instruction and establish if they have any effect on students’ achievement. The researcher was prompted by continuous poor performance in mathematics and yet it is a core subject in the school curriculum. There has been creation of various devices aimed at helping learners to get solutions to mathematical problems starting from counting sticks, abacus, slide rule, mathematical tables and scientific calculators in that order but no tangible evidence to show that scientific calculators will solve the problem in mathematics. Scientific calculators can be more effective than mathematical tables in improving students’ achievement in mathematics and enhancing positive students’ attitudes and motivation towards the subject. Scientific calculators can provide a point of departure to move away from the predominant expository teaching that gives the students very few opportunities to develop practical skills necessary for negotiating meanings, be creative and effectively participate in learning. It can also improve impoverished situation of mathematics instruction in secondary schools.