Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 492 · 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.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) yeast (c) a mirror (d) a small bowl
2. 2.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) it turned into air (c) the paper ate it (d) the ink is magnetic
3. 3.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) almost nothing (c) dark brown words (d) a rainbow
4. 4.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a cotton bud (c) a balloon (d) an adult with an iron
5. 5.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) the same cotton bud (c) how dark the writing is (d) the ironing time
7. 7.🔍 Which is the odd one out? (a) putting the iron away (b) reading the message (c) dipping the cotton bud (d) letting the paper dry
8. 8.True or false: a battery cell is not needed for the secret lemon message. (a) False (b) True
9. 9.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) blue (c) brown (d) green
10. 10.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) writing the message (d) cutting the lemon
11. 11.True or false: putting the iron away is a job for an adult. (a) True (b) False
12. 12.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
13. 13.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) reading the message (c) plugging in the iron (d) ironing the paper
14. 14.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) an adult with an iron (c) a balloon (d) white paper
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) True (b) False
16. 16.True or false: white paper is needed for the secret lemon message. (a) False (b) True
17. 17.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) an adult with an iron (c) yeast (d) white paper
18. 18.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a small bowl (c) a magnet (d) an adult with an iron
19. 19.🍋 Which of these steps is a job for an adult? (a) writing the message (b) reading the message (c) dipping the cotton bud (d) plugging in the iron
20. 20.⚖️ 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
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) False (b) True
22. 22.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) a small bowl (d) a magnet
23. 23.🍋 Which of these steps is a job for an adult? (a) putting the iron away (b) letting the paper dry (c) reading the message (d) writing the message
24. 24.🔍 Which is the odd one out? (a) putting the iron away (b) ironing the paper (c) plugging in the iron (d) letting the paper dry
25. 25.🔮 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
26. 26.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
27. 27.🛟 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
28. 28.🧺 Which of these is not needed for the secret lemon message? (a) a battery cell (b) a cotton bud (c) a small bowl (d) an adult with an iron
29. 29.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
30. 30.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) yeast (c) a magnet (d) white paper
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) False (b) True
32. 32.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if shaken (c) yes, in the dark (d) yes, if cooled
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we change it (c) we keep it the same
34. 34.🔍 Which is the odd one out? (a) ironing the paper (b) putting the iron away (c) cutting the lemon (d) dipping the cotton bud
35. 35.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
36. 36.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
37. 37.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
38. 38.True or false: yeast is needed for the secret lemon message. (a) False (b) True
39. 39.⚖️ 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 iron setting
40. 40.🧺 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 cotton bud (d) a battery cell

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