Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 978 · 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.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) the paper floats (c) writing turns green (d) writing stays faint
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the ironing time (b) the same paper (c) how dark the writing is (d) the kind of juice
3. 3.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a battery cell (c) lemon juice (d) an adult with an iron
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) True (b) False
5. 5.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) a rainbow (c) dark brown words (d) almost nothing
6. 6.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) yeast (c) a magnet (d) lemon juice
7. 7.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a cotton bud (c) a mirror (d) lemon juice
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same cotton bud (b) the iron setting (c) the ironing time (d) how dark the writing is
9. 9.⚖️ 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
10. 10.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
11. 11.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) lemon juice (c) white paper (d) a cotton bud
13. 13.🧺 Which of these is needed for the secret lemon message? (a) an adult with an iron (b) turmeric powder (c) a balloon (d) a magnet
14. 14.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) brown (c) green (d) blue
15. 15.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a balloon (c) a small bowl (d) a battery cell
16. 16.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
17. 17.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
18. 18.🧺 Which of these is not needed for the secret lemon message? (a) a balloon (b) a small bowl (c) a cotton bud (d) lemon juice
19. 19.🛟 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
20. 20.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a balloon (c) turmeric powder (d) a cotton bud
21. 21.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it can burn skin (c) it is cold (d) it is magnetic
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we keep it the same (b) we measure it (c) we change it
23. 23.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) a cotton bud (d) turmeric powder
24. 24.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
25. 25.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
26. 26.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
27. 27.🍋 Which of these steps is a job for an adult? (a) reading the message (b) letting the paper dry (c) cutting the lemon (d) dipping the cotton bud
28. 28.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
29. 29.🔮 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
30. 30.⚖️ 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
31. 31.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
32. 32.True or false: plugging in the iron is a job for an adult. (a) True (b) False
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we measure it (b) we change it (c) we keep it the same
34. 34.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) it turned into air (c) the ink is magnetic (d) dry juice is see-through
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the kind of juice (c) the ironing time
36. 36.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) a magnet (d) an adult with an iron
37. 37.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
38. 38.⚖️ 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 keep it the same (c) we change it
39. 39.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
40. 40.True or false: white paper is needed for the secret lemon message. (a) False (b) True

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