Tense shift is a common mistake made by English language learners when speaking or writing. It happens when they start a text or sentence in one tense, and then shift (or change) to a different tense without any reason.
This often happens in summaries of stories or films. Students are told that it is usual to retell a story in the present tense. After using this tense correctly for one or two sentences, they suddenly change to the past tense for no reason. Here is an example. The shifted tense is shown in bold:
Gopal and his wife are very poor. Every day Gopal goes to the river to catch fish. Sometimes there is no fish in net. Then Gopal and his wife Nataki didn't eat.
Another common occasion when students shift tense is when a sentence has two parts joined by and. For example:
I picked up my bag and go to the library.
Here the student has shifted from past tense (picked) to present tense (go).
Here are two quizzes to practice identifying and correcting tense shift mistakes: