Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 763 · 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.True or false: reading the message is a job for an adult. (a) True (b) False
2. 2.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a cotton bud (c) a magnet (d) a small bowl
3. 3.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) chemical (c) musical (d) magnetic
4. 4.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
5. 5.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a magnet (c) an adult with an iron (d) a cotton bud
6. 6.True or false: letting the paper dry is a job a child can do. (a) False (b) True
7. 7.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) white (c) blue (d) brown
8. 8.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
9. 9.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
10. 10.🍋 Which of these steps is a job for an adult? (a) reading the message (b) letting the paper dry (c) dipping the cotton bud (d) plugging in the iron
11. 11.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
12. 12.🍋 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
13. 13.🔍 Which is the odd one out? (a) reading the message (b) dipping the cotton bud (c) letting the paper dry (d) putting the iron away
14. 14.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
15. 15.⚖️ 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
16. 16.⚖️ 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
17. 17.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
18. 18.True or false: plugging in the iron is a job a child can do. (a) False (b) True
19. 19.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) dipping the cotton bud (c) ironing the paper (d) putting the iron away
20. 20.🍋 Which of these steps is a job for an adult? (a) putting the iron away (b) dipping the cotton bud (c) reading the message (d) writing the message
21. 21.🍋 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
22. 22.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
23. 23.⚖️ 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
24. 24.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
25. 25.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is the one thing we change. (a) False (b) True
27. 27.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it can burn skin (c) it is sticky (d) it is magnetic
28. 28.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a battery cell (c) lemon juice (d) a small bowl
29. 29.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) lick your fingers (c) skip washing (d) rub your eyes
30. 30.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a cotton bud (c) turmeric powder (d) lemon juice
31. 31.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
32. 32.⚖️ 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
33. 33.True or false: letting the paper dry is a job for an adult. (a) False (b) True
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we keep it the same (b) we measure it (c) we change it
35. 35.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
36. 36.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
37. 37.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) letting the paper dry (c) cutting the lemon (d) plugging in the iron
38. 38.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) whoever is fastest (c) only an adult (d) the youngest child
39. 39.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
40. 40.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a battery cell (c) turmeric powder (d) an adult with an iron

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