I developed my English vocabulary learning activity with HotPotatoes, a computer program for creating CALL materials. This activity is designed for senior school students whose English is at a medium level. It serves as a pre-class activity where students familiarize themselves with the topic of the forthcoming class and learn the vocabulary beforehand to prepare for the major lecture. Students are expected to finish the activity outside of class at their own pace. The activity is composed of 9 steps, each serving one purpose of vocabulary learning. My activity addresses mainly the comprehension part of vocabulary learning, according to the distinction made by Nattinger. The first two listening exercises act as a warm-up for students to go fast into English study mode... From step 3, the central part of the activity starts, which is to teach new words... In step 4, students have the same video as the material. This time, they are required just to listen to the video and find the missing words from the drop-down list... Step 5 is for students to find out the meaning of new words by doing matching exercises... Step 6 is another matching exercise with the same purpose of meaning finding... After the meaning finding stepsabove, students come to step 7 in which they have to fill the blanks in a sentence. And the sentence happens to be the explanation of the word... The purpose of Step 8 is to let students review the new words in a cross game and also an attempt to help them remember the spellings... Step 9 is a wrap-up exercise. This time, the focus is on the pronunciation.