Here are some helpful links for reviewing adding fractions:
Video and practice problems: https://www.khanacademy.org/math/in-sixth-grade-math/fractions-1/addition-subtraction-fractions/v/adding-fractions-with-unlike-denominators
Review Game: https://www.sheppardsoftware.com/mathgames/fractions/mathman_fractions_add_uncommon.htm
IXL Practice:
https://www.ixl.com/math/grade-5/add-and-subtract-mixed-numbers-with-like-denominators
https://www.ixl.com/math/grade-6/least-common-denominator
https://www.ixl.com/math/grade-6/convert-between-improper-fractions-and-mixed-numbers