We have used Hot Dots, by Educational Insights, products in our house for over 8 years. My kids look forward to when they get to use them- they are considered special because we do not use them every day.
In order to use the Hot Dots cards, you need a pen. The Hot Dots Pen has a sensor at the bottom that can sense if it is touching a hot dot. On each card, the hot dot is the correct answer. When the Hot Dot Pen comes in contact with a Hot Dot, the pen makes a noise that indicates a correct answer and another noise for an incorrect answer. The pen is designed to help children hold pens and pencils correctly. Many kids find that holding it in correctly is uncomfortable.
When you look at a math card, you are given an equation. The answer is located on the right or left column (circled in red). The answer to the equation on the other side of the card is at the top so that if you want to use the cards like traditional cards, the teacher can see the answer to the question the student is solving (circled in blue).
The Hot Dots Geography cards have two sides. On one side (shown on right), you need to find the correct state. A few state facts are found on this side: State Nickname, when it gained statehood, State bird, and State Flower.
There are also reading cards where you read a passage then answer multiple choice comprehension questions to check for understanding. The phonics digraph card is pretty self-explanatory when you look at the graphic on the right.
In the end, I recommend the Hot Dots Learning System as a great tool for making learning fun and reinforcing skills learned elsewhere. These can be used in conjunction with your home school curriculum or as a summer activity for kids who attend school outside the home.