These games are thought provoking and very engaging. They encourage discussion of place value, mental calculations and estimation, alongside valuable strategic mathematical thinking.
Invite volunteers (perhaps working in teams of two) to play Game 1 on the board and explain the rules to them and the rest of the class.
When the game is over confirm who has won and explain the scoring system.
Working in teams of two, set the students off on playing Game 1. Depending on your aims for the lesson, offer the simple or more complicated scoring system.
You may want to download and hand out this score sheet.
Encourage students to justify their strategies to their partners, and draw their ideas together at the end of the lesson.
Why are some cells more significant than others?
How do you decide which targets are appropriate?
What are effective strategies for placing the numbers?
If pupils are struggling, they might benefit from trying Dicey Addition. This is a simpler version that uses fewer cells in each game.
Perhaps provide students with number cards that they can move around the grid to consider different options.
Pupils who find estimation difficult could use calculators to check their estimates.
Choose the easiest scoring system or allow calculators for scoring the more difficult version.
Allow pairs of students to play against other pairs, so that they can support each other.