Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 261 · 40 questions

What you do (Heat shows the secret): 1. Dip a cotton bud in lemon juice and write a secret message on white paper. 2. Let the paper dry completely — the writing disappears. 3. An adult irons the paper on a low setting while you watch from a safe distance. 4. Read the brown message and wash your hands.

1. 1.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
2. 2.True or false: a magnet is needed for the secret lemon message. (a) False (b) True
3. 3.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it can burn skin (c) it is cold (d) it is sticky
4. 4.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
5. 5.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) the paper floats (c) it gets darker (d) writing turns green
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) True (b) False
7. 7.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
8. 8.🔍 Which is the odd one out? (a) letting the paper dry (b) dipping the cotton bud (c) plugging in the iron (d) writing the message
9. 9.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) white paper (c) turmeric powder (d) a magnet
10. 10.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
11. 11.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
12. 12.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we change it (b) we keep it the same (c) we measure it
14. 14.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
15. 15.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) only an adult (c) whoever is fastest (d) any child
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) False (b) True
17. 17.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) an adult with an iron (c) a small bowl (d) a mirror
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same paper (b) how dark the writing is (c) the kind of juice
19. 19.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) the same cotton bud (c) how dark the writing is
21. 21.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a battery cell (c) a balloon (d) lemon juice
22. 22.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) heat adds colour (c) paper turns lemony (d) the juice scorches first
23. 23.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) an adult with an iron (c) a balloon (d) a mirror
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we measure it (b) we change it (c) we keep it the same
25. 25.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
26. 26.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
27. 27.True or false: writing the message is a job a child can do. (a) True (b) False
28. 28.True or false: an adult with an iron is needed for the secret lemon message. (a) True (b) False
29. 29.True or false: letting the paper dry is a job a child can do. (a) False (b) True
30. 30.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) blue (c) white (d) brown
31. 31.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a cotton bud (c) an adult with an iron (d) a battery cell
32. 32.True or false: a mirror is needed for the secret lemon message. (a) False (b) True
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we measure it (b) we change it (c) we keep it the same
34. 34.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) lemon juice (c) a cotton bud (d) a small bowl
35. 35.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
36. 36.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
37. 37.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
38. 38.🍋 Which of these steps is a job for an adult? (a) reading the message (b) writing the message (c) ironing the paper (d) letting the paper dry
39. 39.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) musical (c) chemical (d) magnetic
40. 40.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, if cooled (c) no, it stays brown (d) yes, in the dark

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