This chart explains how to conjugate regular -ar verbs in the simple present. You take away the ar ending and add the corresponding one to their noun.
PDF Present -ar Regular verbs graphic.
This is a worksheet to practice:
PDF:Practicando el presente indicativo. Verbos regulares -ar
Looking for more worksheets to practice? Check out this great packet available at TPT (Teachers Pay Teachers) for $3.99 HERE. This is a preview. It includes 12 pages with 4 verb practices that increase in complexity.