Exercises and articles about numbers up to 100 — tens and ones, reading numbers and skip counting by 2, 5 and 10. (Part of 1st-grade curriculum in the US, Germany and Spain.)
Exercises and articles on addition and subtraction within 100, with and without regrouping, including column methods.
Exercises and articles on comparing two-digit numbers and ordering numbers up to 100.
Exercises and articles on multiplication tables 1–5, multiplication as repeated addition, and arrays.
Exercises and articles on telling time — hour, half past, quarter past, and five-minute intervals.
Exercises and articles on counting money, coin exchange, and making change — dollars (US) and pounds (UK).
Exercises and articles on 2D and 3D shapes, their sides, vertices, and faces, lines of symmetry, and turns.
Exercises and articles on measuring length (cm, m), weight (g, kg), and capacity (ml, l) — choosing units and comparing.
Exercises and articles on one-step and two-step word problems with addition, subtraction, and multiplication within 100.
Exercises and articles on reading tally charts, pictographs, and bar graphs.
Exercises and articles on division as sharing into equal groups, dividing by 2, 5, and 10, and the link between multiplication and division.
Exercises and articles on the basic fractions — halves, thirds, quarters — when partitioning shapes and groups into equal parts.