Proposal for Math Lesson on March 26

Father and his sons
Father is 41 years old. He has 3 sons. The first one is 13, the second is 10, and the third is 6 years old. In how many years the father's age will be equal to sum of his sons' ages?

How much cake is left for tomorrow?
A cake is cut into 15 equal parts. Michael ate 1/3 of the cake, Jane 2/5 of the cake, and Liz ate 1/3 from what Jane ate. The rest of the cake is left for tomorrow. What part of the cake is left for tomorrow?

Rainy day
There are 10 adults, 20 children, 5 dogs. They are all standing under one tiny umbrella. In what particular case they will not be wet?

How to make a glass half full?
There are three glasses. The first glass can contain maximum 8 oz of water, the second 5 oz, and the third 3 oz. The first glass is full with water. How to make this glass half full?

Twins
In the second grade there are 4 pairs of twins among other children. On Halloween party each child in that class brought dad and mom and they are all in the gym. No other people are in the gym. There are 85 people all together. How many kids in that second grade?

Horses
A pair of horses ran 20 miles. How many miles did each horse run?