ALGEBRA 



LSI 



ALGEBRA 



ALGAE 



(a) Deep-sea "devil's apron" 



(b) Deep purple coralline algae 



(c) Bladder wrack 



(d) A branching red variety 



in fresh water and some in salt, and they vary 

 in size from the microscopic forms to those 

 whose stems resemble the trunks of forest 

 trees, and whose fronds rival the leaves of the 

 palm. The higher species have stems bearing 

 the leaf-like expansions and are often attached 

 to the rocks by roots, but in many species the 

 stems are absent, the whole plant being a 

 mere shapeless, jelly-like mass. As the algae 

 aiv entirely composed of cellular tissue, many 

 are edible and nutritious, as carrageen, or 

 Irish moss, dulse, etc. Kelp, iodine and bro- 

 mine are products of various species and the 

 algae are also valuable as manure. About 

 twelve thousand species are known and these 

 are classified in groups according to their color, 

 being recognized as green, brown or red. Most 

 green algae are fresh-water plants, while the 

 brown and red forms are usually confined to 

 salt water. 



ALGARDI, ALESSANDRO (1602-1654), an Ital- 

 ian architect and sculptor, born at Bologna. 

 His chief work was done in Rome, where he 

 followed the style of his great contemporary, 

 Giovanni Bernini. Algardi made the tomb of 

 Pope Leo XI, in Saint Peter's, and for the 

 same church a representation of Attila's retreat 

 from Rome. The latter is the largest figure in 

 high-relief in the world. His work as an archi- 

 tect is represented by the facade of the Church 

 of Sant' Ignazio. It is as a sculptor that 

 Algardi will be best remembered. 



LGEBRA. A vital element in 

 teaching is the recognition of continuity ot 

 subject-matter. Let us find the continuity be- 

 tween arithmetic and algebra, the points com- 

 mon to the two subjects, where algebra touches 

 arithmetic and belongs with it, and where the 

 two subjects are distinct. Insight into these 

 points makes clear the relation and interde- 

 pendence of elementary school mathematics 

 and early high school mathematics. 



Very early in the elementary school the 

 child is solving such problems as these: 

 7+8=15, 9+7=16; out of this grows 7 and 



what number make 15, 9 and what number 

 make 16, and so on. Following the form 

 above, the teacher writes 7+ (a number) =15, 

 thus translating the problem into good form. 

 , This is algebraic in thought and form, as well 

 1 as arithmetical. It very readily becomes 

 7+n=15. It should be read freely, as follows: 

 "A number has been added to 7 and the 

 answer is 15." Then follows the question, 

 "What is the number?" The problem looks 

 like this when completed: 

 7+n=15 

 n= 8 



