Gimkits are a great warmup activity to use when you want to review a couple topics.
Here are some I've made, I've made many questions for each so they should be able to be played/repeated a number of times.
For the students beginning second JHS year, this should review things from elementary school up until the end of the first topic for second year - https://www.gimkit.com/view/6423719402c8520032c03975
For the students at the end of their second JHS year, this should review many things up until that point, including things learnt at elementary school - https://www.gimkit.com/view/63e57d830bf9080038aa2a9e
For the students at the end of third year, this reviews the entirety of JHS and many things from elementary school - https://www.gimkit.com/view/63cf71c882acda0036b7b519
Hopefully these should help you during the times where teachers turn to you when there's no textbook to do, or as a warm up.
All of these reviews concern grammar included in the New Horizons JHS textooks.