Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 875 · 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 magnet (b) a cotton bud (c) turmeric powder (d) a balloon
2. 2.⚖️ 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
3. 3.True or false: white paper is needed for the secret lemon message. (a) False (b) True
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) False (b) True
5. 5.True or false: yeast is needed for the secret lemon message. (a) True (b) False
6. 6.🔍 Which is the odd one out? (a) writing the message (b) plugging in the iron (c) ironing the paper (d) putting the iron away
7. 7.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) putting the iron away (c) cutting the lemon (d) letting the paper dry
8. 8.True or false: plugging in the iron is a job for an adult. (a) True (b) False
9. 9.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) dry juice is see-through (c) the ink is magnetic (d) it turned into air
10. 10.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) the paper floats (c) writing turns green (d) it gets darker
11. 11.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
12. 12.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
13. 13.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if shaken (c) no, it stays brown (d) yes, if cooled
14. 14.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
15. 15.🛟 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
16. 16.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
17. 17.⚖️ 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 ironing time
18. 18.🔍 Which is the odd one out? (a) writing the message (b) dipping the cotton bud (c) reading the message (d) plugging in the iron
19. 19.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a battery cell (c) white paper (d) a magnet
20. 20.🧺 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
21. 21.🔍 Which is the odd one out? (a) letting the paper dry (b) dipping the cotton bud (c) writing the message (d) ironing the paper
22. 22.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
23. 23.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) skip washing (c) rub your eyes (d) wash your hands
24. 24.⚖️ 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) True (b) False
25. 25.⚖️ 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) how dark the writing is (c) the same paper
26. 26.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
27. 27.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a magnet (c) yeast (d) a small bowl
28. 28.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) an adult with an iron (c) turmeric powder (d) lemon juice
29. 29.⚖️ 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
30. 30.⚖️ 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
31. 31.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) writing the message (c) ironing the paper (d) letting the paper dry
32. 32.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we change it (b) we keep it the same (c) we measure it
34. 34.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a cotton bud (c) a small bowl (d) a balloon
35. 35.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) a cotton bud (d) yeast
36. 36.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a small bowl (c) turmeric powder (d) an adult with an iron
37. 37.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) white paper (c) lemon juice (d) a battery cell
38. 38.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) lemon juice (c) yeast (d) a mirror
39. 39.🔍 Which is the odd one out? (a) plugging in the iron (b) reading the message (c) cutting the lemon (d) ironing the paper
40. 40.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the juice scorches first (c) the iron is brown (d) paper turns lemony

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