About Past Tense
Most English verbs form the past by adding "-ed": walk, walked. But about two hundred of the most common ones do something else entirely. Go becomes went. Swim becomes swam. Past Tense is a quiz on those.
How it works
Each question shows a verb and the start of a sentence: "Yesterday I ___." Three answers are offered. One is the true past tense. Tap it.
After every answer, the game shows the verb in use: "Today I go; yesterday I went." A round is ten verbs, taken from a list of sixty-one.
The wrong answers are of two kinds. One is the form you would get by following the regular rule, such as "goed" or "swimmed". Small children say these, and learners of English often do too. The other is usually the past participle, the form used after "have": "gone", "swum", "eaten". That is the one that catches fluent speakers.
Keeping them straight
Use the sentence. "Yesterday I ___" needs the simple past. "I have ___" needs the participle. So it is "yesterday I swam" and "I have swum", "yesterday I drank" and "I have drunk", "yesterday I began" and "I have begun".
Learn the families. Many irregular verbs follow a shared pattern. Sing, sang, sung. Ring, rang, rung. Drink, drank, drunk. Swim, swam, swum. Begin, began, begun. Another family changes to "-ew": blow, blew; grow, grew; know, knew; throw, threw; fly, flew.
A third group ends in "-ought" or "-aught": buy, bought; bring, brought; think, thought; catch, caught; teach, taught.
Some change only the vowel: win, won; sit, sat; meet, met.
A few are simply strange. "Go" and "went" were once two different verbs.
For anyone learning English, HTML5 games like this one are a painless way to drill what the textbooks list in tables.