Geometry - 4th grade

This is an introduction to polygons for elementary school - approximately 4th grade. I like to give students the exercises of drawing randomly 4, 5, 6, 7, or 8 points on the paper and connecting them to get a polygon. I also show exercises where we divide polygons into new ones, or put together polygons to get new ones.

This is an introduction to polygons for elementary school - approximately 4th grade. I like to give students the exercises of drawing randomly 4, 5, 6, 7, or 8 points on the paper and connecting them to get a polygon. I also show exercises where we divide polygons into new ones, or put together polygons to get new ones.

What is a circle? It is a figure where the distance from the center point to any point on the outer line (circumference) is the same. So, that is why an oval won't classify as a circle. Students need to practice drawing circles of various sizes using a compass. Drawing concentric circles is a fun exercise for them. I show two other drawing exercises: to draw a circle inside a square and then to copy a simple circle design.

This lesson is a starting point for classifying triangles by their angles. A right triangle has one right angle. (What about the other two angles? We'll find out.) An obtuse triangle has one obtuse angle. (What about the other two angles? We'll find out.) An acute triangle has THREE acute angles.

This lesson is a starting point for classifying triangles by their angles. A right triangle has one right angle. (What about the other two angles? We'll find out.) An obtuse triangle has one obtuse angle. (What about the other two angles? We'll find out.) An acute triangle has THREE acute angles.

What is a parallelogram? The definition says it's a figure enclosed by two sets of parallel lines, and that's where we will start. The DEFINITION does not say a thing about its side lengths or angle measures. Those things students can notice or find out for themselves by drawing and measuring. I also draw a bigger copy of a given rhombus, which is a very good drawing exercises for students, and give ideas for more drawing problems on a basic level.

What is a parallelogram? The definition says it's a figure enclosed by two sets of parallel lines, and that's where we will start. The DEFINITION does not say a thing about its side lengths or angle measures. Those things students can notice or find out for themselves by drawing and measuring. I also draw a bigger copy of a given rhombus, which is a very good drawing exercises for students, and give ideas for more drawing problems on a basic level.

I show how you can draw a right angle (or a perpendicular line to a given line) using either a protractor or a triangular ruler. I also show a line perpendicular to a given line, drawn through a point on the line, or drawn through a point not on the line. Lastly, I draw a rectangle with given side lengths, using a protractor to make right angles, and a regular ruler to measure the sides.

I show how you can draw a right angle (or a perpendicular line to a given line) using either a protractor or a triangular ruler. I also show a line perpendicular to a given line, drawn through a point on the line, or drawn through a point not on the line. Lastly, I draw a rectangle with given side lengths, using a protractor to make right angles, and a regular ruler to measure the sides.

Estimating angle measures is based on comparing them to some ballpark angles, such as the right angle, the 45° angle, and the 30° angle (which is the angle between two consecutive numbers on the clock face). First, I estimate a few angles. Then I draw a few angles by estimating them (not measuring), and check afterwards. Lastly in this video I explain the concept of turning in a specific angle, such has turning in a 30° angle.