Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 589 · 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 is the odd one out? (a) ironing the paper (b) cutting the lemon (c) writing the message (d) putting the iron away
2. 2.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) it gets darker (c) the paper floats (d) writing turns green
3. 3.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) the ink is magnetic (c) it turned into air (d) the paper ate it
4. 4.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
5. 5.🔍 Which is the odd one out? (a) letting the paper dry (b) writing the message (c) reading the message (d) ironing the paper
6. 6.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) rub your eyes (c) wash your hands (d) lick your fingers
7. 7.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) the youngest child (c) only an adult (d) whoever is fastest
8. 8.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) yeast (c) a cotton bud (d) a magnet
9. 9.⚖️ 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 ironing time (c) the kind of juice
10. 10.True or false: reading the message is a job for an adult. (a) True (b) False
11. 11.⚖️ 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 kind of juice (c) the same cotton bud (d) how dark the writing is
12. 12.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the iron is brown (c) the juice scorches first (d) paper turns lemony
13. 13.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) no, it stays brown (c) yes, if shaken (d) yes, if cooled
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) True (b) False
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the ironing time (b) how dark the writing is (c) the same cotton bud (d) the same paper
16. 16.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
17. 17.⚖️ 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
18. 18.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) an adult with an iron (c) turmeric powder (d) a magnet
19. 19.⚖️ 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 keep it the same (c) we measure it
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) False (b) True
21. 21.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
22. 22.⚖️ 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
23. 23.True or false: a magnet is needed for the secret lemon message. (a) False (b) True
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) False (b) True
25. 25.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
26. 26.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) letting the paper dry (c) dipping the cotton bud (d) writing the message
27. 27.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) writing the message (c) putting the iron away (d) plugging in the iron
28. 28.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it can burn skin (c) it is magnetic (d) it is sticky
29. 29.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
30. 30.🔍 Which is the odd one out? (a) cutting the lemon (b) reading the message (c) ironing the paper (d) putting the iron away
31. 31.True or false: a battery cell is needed for the secret lemon message. (a) False (b) True
32. 32.True or false: reading the message is a job a child can do. (a) False (b) True
33. 33.🧺 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 mirror (d) a small bowl
34. 34.🧺 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 small bowl (d) yeast
35. 35.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
36. 36.True or false: putting the iron away is a job for an adult. (a) False (b) True
37. 37.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
38. 38.True or false: plugging in the iron is a job a child can do. (a) True (b) False
39. 39.🔍 Which is the odd one out? (a) writing the message (b) dipping the cotton bud (c) reading the message (d) plugging in the iron
40. 40.⚖️ 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

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