### Lesson 4: Base, Altitude, Apex, and Hypotenuse (Form)

The instructor reviews the following terms with children and points out each example in the top image:

- Altitude: The height of a triangle from its base to its apex.
- Apex: The topmost vertex of a triangle.
- Side: A line connecting the vertexes of a triangle.
- Base: The lowest side of a in a triangle or other polygon.
- Hypotenuse: The side of a right triangle opposite the right angle.

Children complete the following drill work:

- Draw an acute triangle and label its base, apex, and sides.
- Draw an obtuse triangle and add a dotted line to represent its altitude.
- Draw a right triangle and label its hypotenuse.
- Draw an equilateral triangle and label its base and sides.
- Draw a rectangle and mark and label the diagonals.
- Draw a square and mark and label the diagonals.
- Draw an equilateral triangle with the apex pointing upward.
- Draw an equilateral triangle with the apex pointing downward.