Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 517 · 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.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) lemon juice (d) yeast
2. 2.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
3. 3.⚖️ 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
4. 4.🔍 Which is the odd one out? (a) cutting the lemon (b) reading the message (c) plugging in the iron (d) ironing the paper
5. 5.⚖️ 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 iron setting (c) how dark the writing is
6. 6.True or false: yeast is needed for the secret lemon message. (a) True (b) False
7. 7.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) blue (c) green (d) brown
8. 8.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
9. 9.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) ironing the paper (c) reading the message (d) dipping the cotton bud
10. 10.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) lick your fingers (c) skip washing (d) wash your hands
11. 11.🔍 Which is the odd one out? (a) writing the message (b) letting the paper dry (c) cutting the lemon (d) dipping the cotton bud
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is the one thing we change. (a) True (b) False
13. 13.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) plugging in the iron (c) letting the paper dry (d) ironing the paper
14. 14.🔮 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
15. 15.⚖️ 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
16. 16.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it is magnetic (c) it can burn skin (d) it is sticky
17. 17.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) the paper ate it (c) dry juice is see-through (d) it turned into air
18. 18.⚖️ 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) how dark the writing is (c) the kind of juice (d) the same cotton bud
19. 19.🧺 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 magnet (d) white paper
20. 20.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) physical (c) musical (d) chemical
21. 21.True or false: letting the paper dry is a job a child can do. (a) False (b) True
22. 22.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we keep it the same (b) we measure it (c) we change it
24. 24.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we keep it the same (b) we measure it (c) we change it
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) lemon juice (c) a small bowl (d) a cotton bud
27. 27.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) a rainbow (c) blue words (d) almost nothing
28. 28.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a magnet (c) turmeric powder (d) lemon juice
29. 29.🍋 Which of these steps is a job for an adult? (a) writing the message (b) letting the paper dry (c) putting the iron away (d) reading the message
30. 30.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
31. 31.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a cotton bud (c) turmeric powder (d) a mirror
32. 32.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing stays faint (c) the paper floats (d) writing turns green
33. 33.🍋 Why does the lemon writing turn brown with heat? (a) the juice scorches first (b) heat adds colour (c) paper turns lemony (d) the iron is brown
34. 34.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) writing the message (c) ironing the paper (d) cutting the lemon
35. 35.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) False (b) True
37. 37.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) white paper (c) turmeric powder (d) a cotton bud
38. 38.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
39. 39.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
40. 40.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed

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