Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 272 · 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) a child can do it (b) an adult does it
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the kind of juice (b) how dark the writing is (c) the iron setting (d) the same paper
3. 3.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) it gets darker (c) the paper floats (d) writing stays faint
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) an adult with an iron (c) a battery cell (d) a cotton bud
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same paper (b) the iron setting (c) the kind of juice (d) the same cotton bud
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is the one thing we change. (a) True (b) False
7. 7.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) lemon juice (c) a balloon (d) a cotton bud
9. 9.🔍 Which is the odd one out? (a) ironing the paper (b) putting the iron away (c) cutting the lemon (d) reading the message
10. 10.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is sticky (c) it is cold (d) it can burn skin
11. 11.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) skip washing (c) lick your fingers (d) rub your eyes
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we change it (b) we measure it (c) we keep it the same
13. 13.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
14. 14.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) no, it stays brown (c) yes, if cooled (d) yes, in the dark
15. 15.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) white (c) brown (d) green
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we measure it (c) we keep it the same
17. 17.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
18. 18.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
19. 19.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) white paper (c) a balloon (d) a mirror
20. 20.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) only an adult (c) whoever is fastest (d) the youngest child
21. 21.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
22. 22.True or false: yeast is not needed for the secret lemon message. (a) False (b) True
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) True (b) False
24. 24.True or false: writing the message is a job for an adult. (a) True (b) False
25. 25.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the paper ate it (c) the ink is magnetic (d) dry juice is see-through
26. 26.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
27. 27.🔍 Which is the odd one out? (a) reading the message (b) plugging in the iron (c) letting the paper dry (d) writing the message
28. 28.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) yeast (c) turmeric powder (d) a cotton bud
29. 29.🍋 Which of these steps is a job a child can do? (a) reading the message (b) cutting the lemon (c) ironing the paper (d) plugging in the iron
30. 30.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) lemon juice (c) a magnet (d) an adult with an iron
31. 31.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) almost nothing (c) dark brown words (d) blue words
32. 32.True or false: letting the paper dry is a job a child can do. (a) True (b) False
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is kept the same. (a) False (b) True
34. 34.True or false: putting the iron away is a job a child can do. (a) False (b) True
35. 35.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) a mirror (d) an adult with an iron
36. 36.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) turmeric powder (c) white paper (d) a cotton bud
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) False (b) True
38. 38.True or false: reading the message is a job a child can do. (a) False (b) True
39. 39.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) writing the message (c) cutting the lemon (d) letting the paper dry
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) True (b) False

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