No matter what unit of science you're teaching, make up questions and divide students into two or more teams to answer them. When a team gets a correct answer, they have the opportunity to play "basketball" with a bean bag: students throw the bean bag into an empty trashcan or bucket. If they make the basket, their team gets a point.
Make cards for definitions or content questions. Put the question on one index card, and the answer on another. Do this with each question and answer. Turn all of the cards face down and mix them around. Have students take turns turning over two cards at a time. If the cards do not match with the correct question and answer, the cards must be turned face down. When a student matches the question and correct answer, he picks up the cards and puts them in his stack. The student with the most cards at the end of the game wins.
There are several ways to make a Jeopardy type game for science review. One way is to put categories on the board and have students choose a category and dollar amount. Make sure you have prepared answers. When a student chooses a category, read the answer and the student gives the question.
Use science words and phrases to make a Wheel of Fortune game. Students can take turns guessing letters until one can identify the correct word or phrase. Some websites allow teachers to put in the phrases or words they want their students to identify. Students then spin the wheel and guess letters. This is a good option because teachers can link the game to their class page or load it on classroom computers for students to play at home or in their free classroom time.