Watch the videos below about the alkali metals and the halogens. Write a ½ - 1 page discussion of the similarities and differences in the chemical properties of elements in these two groups. Specifically discuss the reactions of the Alkali metals (Li, Na, K) with water and with the halogens (Cl2, Br2, I2). And the Halogens (Cl2, Br2, I2) with halide ions (Cl-, Br-, I-).
On the other resources page see Periodic Table of Videos for great vids on specific elements if you would like.