### How it Works:

The Head-to-Tail Vector Addition Concept Builder is quite simple to use. Every question is identical. You are given a vector addition equation involving the addition of three vectors. A diagram of each vector is shown. You have to identify what the correct vector addition diagram looks like. There are six options to pick from. To view an option, you have to tap on the diagram shown below the equation. Each time you tap, a new answer option is displayed. After viewing all six options, additional taps recycle through the six options a second time from the beginning. Once you are satisfied with your selection, tap on the Check Answers button. Feedback will be immediate and your Progress Report will be updated. Your goal is to successfully analyze each of the Question Groups at each particular difficulty level.

There are three different levels of difficulty. Your goal is to earn "Stars" and to complete one or more difficulty levels. Stars are earned when you show success on a particular question. Once you show success on all the questions at a particular difficulty level, you will earn the medal for that level.

### Earning Stars

When you start up any level of difficulty, the number of questions for that level are shown in the Progress Report area of the Concept Builder. You will notice that there is either a Yellow or a Red background for each question number. When starting up a difficulty level, the background color is Yellow. Answering a "Yellow" question correctly earns you a star for that question number. However, answering it incorrectly turns the background color to Red. A question number with a Red background must be correctly answered twice (without a miss) in order to earn a star.

### Getting Help

You will notice that there is a Help Me button underneath the Progress Report. You should learn to use this feature of the program. It's how you can turn an exercise in answering questions into an exercise in learning. Tapping on the Help Me button will open a page with help that is specific to the task. Of course, the Help pages are only helpful if you read them. So take the time to read them. Each Help page contains four sections: a discussion of the The Basic Idea, a display of the Question your are facing (or a similar question with different numbers), a section titled "How to Think About This Situation", and a set of links to resources in our Tutorial section. You should pay attention to the section titled How to Think About This Situation. You will find what you need to know in the three or four paragraphs of this section. You will also become a better Physics student for doing that. That is, after all, the goal of such an activity as Head-to-Tail Addition​.

Thanks for being patient with the Directions. Happy learning!