In recent years, measurement estimation became part of the mathematics curricula in Germany. At the same time it became obvious that little is known about the abilities of children in this field, especially on primary level. Since most research in measurement estimation is focused on lengths and mainly on older students (Sowder 1992), we focused on younger children and included lengths as well as another measurement area. Our tasks were constructed with reference to Bright’s (1976) typology of requests in estimating length. In each measurement area and four types of requests five tasks were constructed, so overall 40 estimation tasks were presented. 46 (27 ♀; 19 ♂) 4th-graders from different schools solved these tasks in individual interviews which lasted about 15-20 minutes and were videotaped. Although strategies in estimating lengths are labeled differently by different authors (Hildreth 1983; Joram et al. 2005; Siegel et al. 1982), using benchmarks as reference points, iterate mentally a unit or decompose and recompose the to-be-estimated object mentally can be extracted from most studies. The results of our study show that 4th-graders can make use of a variety of different strategies to estimate lengths and capacities. All strategies known from literature could be observed in our data as well. We could specify all of them into different subgroups as well as describe some more. The strategies to estimate capacities are mainly the same as those to estimate lengths. The poster will show in detail the tasks and the categorical system of strategies, which in some sense is depending on the measurement area as well as on the task environment. References Bright, G. W. (1976). Estimation as Part of Learning to Measure. In D. Nelson & R. E. Reys (Eds.), Measurement in School Mathematics (pp. 87-104). Reston: NCTM. Hildreth, D. J. (1983). The Use of Strategies in Estimating Measurements. The Arithmetic Teacher 30(5), 50–54. Joram, E.; Gabriele, A. J.; Bertheau, M.; Gelman, R.; Subrahmanyam, K. (2005). Children's Use of the Reference Point Strategy for Measurement Estimation. Journal for Research in Mathematics Education 36(1), 4–23. Siegel, A. W.; Goldsmith, L. T. & Madson, C. R. (1982). Skill in Estimation Problems of Extent and Numerosity. Journal for Research in Mathematics Education, 13(3), 211-232. Sowder, J. (1992). Estimation and Number Sense. In D. A. Grouws (Ed.), Handbook of Research on Mathematics Teaching and Learning (pp. 371-389). Reston: NCTM.