The teacher's guide for unit four of a Spanish science/math strand for second graders contains instructional and assessment activities for kits 13-16. Each designed for a two- to three-week teaching period, the kits' activities are geared toward guiding the child to discover correct answers through methods provided and, by putting materials in his hands, helping him discover facts through participation and use of reasoning powers. The guide lists focus, objective, and materials in English and Spanish for each learning activity; teacher instructions are in Spanish. Specific activities cover volume--gallon, quart, pint; fractions one-half and one-quarter; "more than" and "less than" symbols; comparatives "shorter than" and "taller than"; addition and subtraction combinations--missing addends, subtrahends, and operational symbols; commutative principle; subtraction as inverse of addition; parenthesis in addition combinations; plants--classification and germinations of seeds, function of parts of a plant, plant identification, usefulness to man; addition and subtraction of sets of 10-19 elements; missing addends and subtrahends; animals--characteristics, habits, usefulness to man; longitude--inches, feet, yards; three dimensional forms; counting by ones to 100; the five senses; change caused by environment and growing older. (RS)