Here's a picture that can give you an idea what base times height divided by 2 looks like:

Every triangle is half of a parallelogram. We know the formula to find the area of a parallelogram is base times height. So the formula for the area of a triangle is half the area of a parallelogram. Formula for area of a triangle is base times height divided by 2.
Height of a triangle is a perpendicular line from the base to opposite angle.
Here are some pictures for how it looks like:


Here is a video you can watch to help you:
The homework for today is in your homework booklet pages 36-37
Hope this helps you! :) Please comment on anything that you liked or things I need to improve on! Thank you.