The useful skill

The skill that I found most useful was the Venn diagram.  I not only use the Venn diagram in Math for teachers, but in Introduction to Teaching.  The Venn diagram is useful in comparing and contrasting. However, in math for teachers, the venn diagram can be used with the same concept in mind.  I learned this concept rather quickly because it was of great interest to me.  We used the Venn diagram in finding the GCF and the LCD.  The Venn diagram can be used in many different courses.  I will use this concept with many of my students. 

Congratulations!

Titania, you were the first. Very good!